See Saturn during the fall break

As a special treat, the Round Tower will open the newly restored Observatory every evening during the autumn holiday. Come and gaze at the night sky through the large telescope while our astronomers guide you through the wonders of the universe. With a little luck, you may even spot Saturn and its rings.

At long last, the Round Tower can once again open the doors to the Observatory at the top of the tower, which has been undergoing restoration since January. At the same time, autumn has crept in and brought the darkness with it, meaning that it is once again possible to observe planets and stars.

To celebrate the reopening of the top of the Round Tower – and the chance to put your eye to the telescope and gaze out at the night sky – we will be open especially from Monday to Friday, 6–9 pm, during the autumn holiday. Weather permitting, you will, among other things, have the opportunity to see Saturn and its beautiful rings.

The Observatory is a public observatory, which means that everyone – young and old – is welcome to look through the telescope and explore the universe. The Observatory is staffed by two experienced astronomers who can tell you all about everything from stars and planets to Ole Rømer and astronomical instruments – and guide you as you put your eye to the telescope.

Also visit the exhibition about light echoes

If you visit the Observatory the Library Hall halfway up the tower will also be open, just as it is during the day. Here, you can experience the exhibition about Ole Rømer and the great discovery of the finite speed of light, as well as the scientific exhibition Light Echoes, which explores, among other things, a light echo from Tycho Brahe’s discovery of Stella Nova, observed more than 400 years later.

If the weather does not allow us to see either Saturn and its rings of ice and rock particles or the Moon, the Observatory will still be open. Here, the astronomers will tell you more about the historic domed building, the night sky and the nearly 100-year-old telescope.

If you are not able to visit during the autumn holiday, don’t worry. The Observatory is open from October through March on Mondays and Tuesdays from 6–9 pm. Read more about opening hours and which planets may potentially be visible at different times here.

Visiting the Observatory is included in the regular admission price, and your ticket also gives you access to the rest of the Round Tower. Tickets can be purchased at the entrance. As always, children enter free of charge.

Workshop: Make your own artwork with light and cyanotype

Explore the magic of light and take home beautiful works of art when the Round Tower opens its doors to a creative cyanotype workshop on the first Sunday of the autumn holidays.

Come and create celestial images during the autumn holidays. Cyanotype, also known as blueprinting, is an early photographic technique that creates unique images in shades of blue using light and iron-based chemicals. The technique is easy to try: a light-sensitive solution is applied to paper or fabric, objects such as plants are placed on top, the material is exposed to sunlight or UV light, and finally rinsed in water.

On the first Sunday of the autumn holidays, bring your family or a good friend along, make your way up the Round Tower, and try your hand at creating beautiful blue images — naturally with a celestial theme.

Everyone is welcome

The workshop is led by Mai-Britt Amsler, a graphic designer and illustrator from the Design School, who is experienced in teaching techniques including screen printing and cyanotype. Everyone, regardless of experience level, is welcome to join, and the tower provides all the necessary materials. Of course, you can take your artwork home with you.

The workshop is a drop-in event from 12 noon to 4 pm. Please note that there may be a waiting time when there are many visitors at once. The workshop is included in the regular admission fee, which also gives you access to the current exhibitions, a trip to the top for the spectacular view, and a little taste of history along the way.

Hunt for monsters in the night sky

Every day during the Golden Days Festival, from 4 to 20 September, the Round Tower invites children and adults on a monster hunt across the night sky, where the monsters hide among the constellations above us.

Thousands of years ago, people found patterns among the stars. They connected them to stories about terrifying creatures, brave heroes, and magical beings.

During the Golden Days Festival, which this year has the theme “monster,” children and adults can go monster hunting in the Spiral Ramp at the Round Tower. All the way up, a number of constellations are hidden in the tower’s windows, each carrying its own “spooky” story. You can, of course, read more about them while trying your hand at drawing the constellation on a sheet of paper that you can pick up at the bottom of the tower.

For example, learn about the terrifying sea serpent Hydra, with its nine heads, which struck fear and terror into the hearts of people in ancient Greece, as well as the poisonous scorpion and its nemesis — the warrior Orion.

Culture Night with stargazing, winning photos and lighttrail

Finally, the newly restored Observatory is ready to welcome visitors, and the tower’s skilled astronomy guides are ready to take you on a journey into space. It is just one of the highlights of this year’s Culture Night programme at the Round Tower, where you can also see a unique collection of photographs on display in the Spiral Ramp.

This year, the Round Tower is celebrating the 350th anniversary of Ole Rømer’s discovery of the speed of light. That is why Culture Night 2026 will be an evening dedicated to light. We will illuminate the tower from bottom to top through the Spiral Ramp and turn our thoughts towards the universe.

The light will lead visitors up to the Observatory, which has reopened to the public following an extensive restoration. Here, visitors will have the opportunity to look through the historic, newly restored telescope and gaze out into the evening sky. If the weather permits it, there is a good chance that Saturn, among other celestial objects, will be visible.

At the Observatory, our astronomy guides will be on hand to help visitors navigate the night sky and explain what they are seeing through the telescope.

Winning Images and Astronomy Outreach

The illuminated Spiral Walk will also feature the winning images from the major photography competition that visitors to the Round Tower have been able to enter throughout the year. The competition has focused on the unique architecture of the complex and the special role that light plays within it.

As they make their way up through the Spiral Ramp, visitors will encounter the Round Tower’s astronomy guides, who will use engaging presentations and visual tools to share fascinating insights into the sun, moon, and stars.

Halfway up, in the Library Hall, visitors can experience two exhibitions exploring the theme of light. On the way into the hall, they will first encounter this year’s introductory exhibition, Ole Rømer and the Great Discovery, which tells the full story of the scientist and former director of the Round Tower, Ole Rømer, and his revolutionary discovery of the speed of light.

Inside the Library Hall, the fourth and final exhibition in this year’s series exploring light unfolds. Light Echoes brings together artists, curators, and astrophysicists in an exhibition exploring how the connection between light and time shapes our understanding of cosmic phenomena. Through four installations and an immersive soundscape, scientific knowledge unfolds as an experiential and immersive field rather than a fixed image.

There is limited capacity both in the Round Tower and at the Observatory, so please be aware that queues may occur.

Please note: The Round Tower cannot guarantee that celestial objects will be visible through the telescope if weather conditions do not permit it. If the weather is unsuitable, the Observatory will still be open, and the Round Tower’s astronomers will share more about the Observatory and its impressive telescope, which can magnify objects between 80 and 450 times.

Please note: Admission is only possible with a Culture Pass on this evening. The Culture Pass will be available in early October.

Workshop: Paint Black Holes with Light

Meet researchers from the Center for Gravity at the Niels Bohr Institute and explore the fascinating world of gravity as we create striking images of black holes painted with light.

A black hole is a region in space where gravity is so strong that nothing can escape – not even light. Yet scientists can still study them by observing their surroundings: watching stars orbit them, detecting ripples in spacetime when black holes collide, and even capturing images of light bending around them. In this workshop, you’ll discover how researchers observe black holes and learn more about these mysterious cosmic phenomena.

With guidance from experts from the Center for Gravity at the Niels Bohr Institute, you’ll design your own black hole on paper before bringing it to life by painting it with light. By keeping a camera’s “eye” open for a long time, it can collect more light – the same technique used to capture spectacular images of distant nebulae and galaxies. Using this method, along with a variety of light sources including flashlights and fairy lights, you’ll create your very own black hole. Afterwards, your finished image will be sent to your phone, or to the phone of the adult accompanying you, so you can keep it as a souvenir.

The workshop is part of Black Hole Week, organised by the Center for Gravity, a Center of Excellence at the Niels Bohr Institute dedicated to research into gravity, black holes and the most extreme phenomena in the universe.

The workshop takes place at Rundetaarn, is included in the standard admission ticket, and requires no advance booking. The workshop facilitators speak both Danish and English.

guests will also have the opportunity to explore the exhibitions Refractions of Ice and Ole Rømer and the Great Discovery, Rundetaarn’s introductory exhibition. Visitors are also welcome to walk up the beautiful Spiral Ramp to the top of the Tower and enjoy the panoramic views over Copenhagen.

The workshop is part of Rundetaarn’s LIGHT YEAR 2026 programme, marking the 350th anniversary of Ole Rømer’s discovery of the speed of light.

Monster workshop with Shane Brox

Fangs, scales, or a serpent’s tongue? Bring mysterious and monstrous creatures to life when multi-artist Shane Brox invites you to an imaginative and creative monster workshop at the Round Tower.

Using quirky materials, colors, and shapes, children and adults can create their very own monsters with exactly the features they find most frightening. The workshop is a playful free space where imagination takes the lead, and where even the strangest ideas can become fantastic and terrifying creatures.

Shane Brox is a multi-artist who has created television programs and written children’s books. He makes sculptures in many different forms and sizes, working especially with recycled materials. Throughout the workshop, Shane will offer help, advice, and creative ideas.

The workshop requires no registration and is open to all little monsters and their grown-ups, with drop-in access throughout the event. Participation costs only the regular admission fee to the tower, and all materials are provided. Come and enjoy some spooky fun!

Also visit the exhibition

Need a breather? Take a walk through the current exhibition Refractions of Ice and explore patterns of ice crystals under polarized light. Perhaps the colorful, melting ice crystals will inspire your monster creation?

The workshop is part of the Golden Days Festival, where this years theme is “Monster.”

In Ole Rømer’s footsteps

Go hunting for celestial objects and astronomical instruments in the winding Ramp, and help Ole Rømer make his great discovery.

How did Ole Rømer discover that light has a speed? And what did he need in order to figure it out?

Children and the young at heart can explore the Ramp’s windows and collect stickers to learn more about Ole Rømer’s discovery of the speed of light, the 350th anniversary of which is being marked this year by the Round Tower.

In the Library Hall, halfway up, you can also learn more through the exhibition Ole Rømer and the Great Discovery and explore the current special exhibition too!

The children’s activity runs during school holidays for the rest of the year as part of Light Year 2026.

Create Stunning Blue Images with Cyanotype

Experience the magic of light in this family workshop.

How can light create images in captivating shades of blue? You and your family can find out when the Round Tower, in connection with the photo exhibition Ad Lucem, invites children and adults to a creative workshop.

Together with artist Cecilia Ömalm and astronomy professor Göran Östlin—the creators of the exhibition—you’ll have the chance to make your own light prints using cyanotype, a historical photographic technique invented by astronomer John Herschel. The technique traditionally uses iron salts mixed into UV-sensitive solutions which, together with sunlight, form images in characteristic deep-blue tones.

In this workshop, we work with UV light and small glass negatives featuring space-themed motifs, which we will transform into beautiful cyanotypes.

Join us for a creative family workshop that brings together art, science, and curiosity—where you’ll learn the technique and take home your own blue masterpieces! With the same ticket, you can also explore the exhibition and the rest of the Round Tower.

Lantern Walk for Children

Join us for a special evening for families with children in the Round Tower, where we brighten the darkness and create artistic lanterns.

Have you ever experienced the Spiral Ramp in the dark? Find your way to the open workshop in the Library Hall, where you can craft your own imaginative lantern to help you find your way further up through the tower.

Afterwards, you can go exploring with your glowing lantern — and with your parents — in hand, all the way to the top of the old tower.

Please note: This event is for families with children only and is part of the programme for LIGHTYEAR 2026 at the Round Tower — a full year in which we celebrate light and the 350th anniversary of Ole Rømer’s groundbreaking discovery of the speed of light.

Workshop: Paint with Light

Join us as we play with light and long exposure times to create beautiful images together with astrophysicist and head of the Round Tower’s observatory, Christina Toldbo.

What is light? And how did the Danish astronomer Ole Rømer discover 350 years ago that light has a speed? Get the answers when the Round Tower’s observatory director, Christina Toldbo, tells more about astronomer Ole Rømer and his major discovery, which remains important to us today.

When we capture light from the Universe with our bare eyes, there’s a limit to how long we can keep them open. Luckily, we have cameras that can collect light for much longer! This is why astrophotographers can take stunning photos of faintly glowing nebulae and galaxies.

In this workshop, we’ll also use cameras to collect light and create light art with long exposure times and different light sources — including flashlights and Christmas lights! You’ll even get to print your own light-art photo and take it home with you.

Workshops will be held on both February 9 and 10 from 11:00 to 13:00.
Participation is free once admission to the Round Tower has been paid.