In 2026, Rundetaarn (The Round Tower) commemorates the 350th anniversary of Ole Rømer's landmark discovery of the finite speed of light with an extensive year-long programme. The tower's historical introductory exhibition runs from February through the end of the year, taking visitors through the story of the discovery, the man behind it, and Rømer's personal connection to the Round Tower itself.
The exhibition invites visitors to consider key questions: How did Rømer arrive at his conclusion? What does this discovery mean for science today? And who was the man behind the wig — a figure of many talents beyond his most famous achievement?
Alongside the permanent introductory display, four rotating special exhibitions on the theme of light will be presented at intervals throughout the year, offering fresh perspectives each season. Together, they provide deeper insight into Rømer's life, his era, and the broader significance of his work.
The journey spans from Copenhagen's historic Latin Quarter to the court of the Sun King in France, contextualising Rømer's discovery within the political and intellectual world of the 17th century.
Visitors should be aware that the Library Hall (Bibliotekssalen) may be temporarily closed during events or while special exhibitions are being installed. Up-to-date closure information is listed at the top of the landing page at rundetaarn.dk before each visit.