Restoration
Round Tower Observatory to be restored in 2026
This January, we’re stepping into history in real time when the three-tonne observatory dome at the top of the Round Tower is carefully lifted down for a full restoration. It is a rare event and an important step towards securing the future of Europe’s oldest functioning observatory building and Christian IV’s vision of a place to study the sky in the heart of Copenhagen.
Christian IV originally built the Round Tower as “Copenhagen’s Royal Star Castle”, with the purpose of creating an observatory where astronomers from the University of Copenhagen could study the sky above the city’s rooftops. The dome at the top of the Round Tower serves as the roof of the observatory and can be opened to allow both observers and visitors to point the telescope into the night sky. The Observatory at the top has changed many times since the tower was completed in 1642, but the current public observatory and telescope date from 1929.
In 2026, the dome and telescope will be carefully restored to preserve this unique cultural heritage. The copper roof needs mending, and the restoration work will secure the building for many years to come. At the same time, we’re also giving the interior space under the dome some care, including new floors and repairs to the old refractor telescope.
Follow the restoration project right here – with the latest news, history of the Observatory, practical information such as changes in opening hours and temporary closures, and answers to any questions you may have about the visitor experience.
Schedule and important dates
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The telescope will be dismantled and restored. This work will be carried out by specialists in Germany and will take approximately six months. The Observatory will remain closed from this date and throughout the restoration period.
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Scaffolding will be erected around the Observatory between December 8 and 12, which is why the top of the Round Tower – the Viewing Platform – will be closed on these days. However, you can still walk the iconic Spiral Ramp and experience the rest of the tower. Scaffolding is hoisted up by crane, and roads and pathways may be temporarily closed off.
A scaffolding tower will be erected north of the tower as an access route for materials. -
The entire Round Tower will be closed during this period, while other repairs and maintenance are carried out in the tower, including limewashing the Spiral Ramp.
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The dome is expected to be hoisted by crane in the early hours, weather permitting. The area around the tower will be fenced off, and a small construction site will be set up at the base. From there, visitors and passers-by will be able to follow the work up close occasionally and see the dome at street level until April.
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The Round Tower will reopen to visitors with a festive program marking Ole Rømer’s discovery of the speed of light. The Observatory will remain closed.
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The fully restored dome is expected be hoisted back up to the top of the tower at the end of April. Both full and partial closures are likely to occur during this process.
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The scaffolding is dismantled and the telescope is installed.
Both full and partial closures are likely to occur during this process.
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When autumn returns in October, the darker evenings will once again make it possible to view stars and planets from the top of the tower — now with a beautifully restored dome and newly remounted telescope.
