Rundetårn dome restoration is under way in central Copenhagen, after the landmark’s three-ton copper dome was lifted down by crane on Monday morning and placed at street level for a months-long repair programme. The work is aimed at stopping water leaks in the observatory and protecting one of Denmark’s best-known historic buildings, which is part of the Trinitatis complex (Trinitatis Kirke).
Inside the Rundetårn dome restoration project
Rundetårn’s management says the copper roof had started letting water in after decades exposed to wind and weather, with damage traced and assessed over the past two years. The restoration plan was developed with the architectural firm Fogh & Følner and in dialogue with the Danish Agency for Culture and Palaces (Slots- og Kulturstyrelsen) and the Copenhagen Diocese (Københavns Stift).
The overall budget is estimated at DKK 6 million (about €0.80 million), financed by Rundetaarn’s own funds. Rundetaarn is owned by Trinitatis Church (Trinitatis Kirke) and operates as a self-financed cultural institution.
A 10-minute lift, 40 metres down to street level
The copper dome, which has crowned the tower since 1929, was lowered in one piece with a crane in the city centre. Rundetårn had said the lift itself would take around 15 minutes, but Danish media reported it was completed in about 10 minutes, after conditions were checked early in the morning.
Because the operation depended on wind and weather, the final go-ahead was taken on the day. Rundetårn also asked for drone activity around the crane to be minimised for safety and operational reasons.
Why the copper dome had to come down
The dome’s copper cladding had become vulnerable to water penetration. The objective is to stop moisture from reaching the observatory space and to repair any related damage.
Rundetårn’s director (direktør) Jeanette Bursche said the decision reflects “timely care” for a landmark that is both a tourist destination and an active cultural site.
What will be restored: copper, wood and the 1929 telescope
According to the project description, the restoration includes:
- Replacing the copper cladding and repairing the underlying wooden structure of the rotating dome, including the shutter elements.
- Renewing copper at the junction where the dome meets the observatory building.
- Replacing steel guides and support feet with stainless steel components.
- Refurbishing the observatory interior, including a new floor and additional repairs.
- Continuing work on the 1929 telescope, including refurbishment and a lens replacement handled by specialist expertise in Germany.
Rundetårn has also planned related maintenance in the tower, including works on the main passage up to the platform and repainting/whitewashing parts of the internal vaults.
A restoration you can watch from the street
A notable element of the project is that much of the work on the dome will happen at street level next to the tower, at the corner where Landemærket meets Købmagergade. For passers-by, it turns a normally hidden conservation process into a visible workshop, with copper and carpentry work expected through winter and spring.
Rundetaarn notes this is also a way to highlight the craft and planning required to conserve historic buildings in dense city centres.
What visitors can expect in early 2026
Rundetårn is closed throughout January and is expected to reopen on 6 February 2026. The observatory remains closed during the restoration period.
The current schedule foresees dome work on the ground from January to April, with reinstallation planned for April or May, depending on weather. The observatory and telescope are expected to return later in 2026, with reopening targeted for the darker months when the telescope can operate.
Lysår 2026 and the Ole Rømer anniversary
The restoration runs alongside Rundetårn’s 2026 programme “Lysår 2026”, marking the 350th anniversary of Danish astronomer Ole Rømer’s measurement of the speed of light. Rundetaarn’s plan is to fold the restored observatory and telescope back into that programme once the dome returns and the site is fully operational again.
Taken together, the temporary removal of an iconic skyline feature underscores a broader point that Nordic cities increasingly face: maintaining heritage infrastructure while keeping cultural venues open and accessible. In Copenhagen, the short-term visual absence of Rundetaarn’s dome is designed to secure the tower’s long-term role as both a landmark and a working observatory.
