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 Rundetårn.

In the Library Hall, halfway up, you can also learn more through the exhibition Ole Rømer and the Great Discovery and explore the beautiful blue-toned photo exhibition Ad Lucem.

After 4 pm, the light installation While the Light Hesitates is illuminated at the top of the tower, interpreting Ole Rømer’s discovery of the speed of light through both sound and light shining out over the city.

The children’s treasure hunt runs until 6 April and during school holidays for the rest of the year as part of Light Year 2026.