Ole Rømer and the Great Discovery

In 2026, the Round Tower marks the 350th anniversary of Ole Rømer’s groundbreaking discovery of the speed of light with an extensive programme. From February and throughout the year, visitors can experience the tower’s historical introductory exhibition, which tells the story of the discovery, the person behind it, and Rømer’s connection to the Round Tower.

350 years ago, the astronomer Ole Rømer made his pivotal discovery that light has a finite speed. But how did he arrive at this conclusion? What does the discovery mean for us today? And who was he beyond this achievement—the man with many talents and a large wig?

Alongside four rotating special exhibitions on light presented over the course of the year, you can experience the Round Tower’s own exhibition on Ole Rømer and gain deeper insight into the man, the discovery, and his relationship to the Round Tower.

Group Tours: Explore Rømer and the Round Tower

In 2026, the Round Tower will also introduce a brand-new guided tour programme. From week 8, our team of guides will be ready to welcome private groups and educational institutions for tours of the historic tower.

Book a special Ole Rømer tour developed in connection with Light Year 2026 and gain insight into the life and work of the world-renowned astronomer at the Round Tower—naturally including his discovery of the speed of light.

Booking is expected to open in January via the Round Tower’s webshop.