The Round Tower (Rundetaarn)

The Round Tower, Rundetaarn, was built by King Christian IV between 1637 and 1642 as an astronomical observatory for the university, and it is now one of the most recognisable buildings in the old town. It forms part of the Trinitatis complex together with the Trinitatis Church and the university library hall above it, and it still contains a working public observatory, making it one of the oldest functioning observatory buildings in Europe.

Instead of stairs, the tower is climbed by a broad spiral ramp that winds seven and a half times around a hollow core for just over 200 metres. The ramp is so wide that Tsar Peter the Great is said to have ridden up on horseback in 1716. The ramp is gentle enough for most visitors, and on the way you pass the Library Hall, which has been used for exhibitions and concerts since 1987. The current programme includes an exhibition about the Danish astronomer Ole Rømer. At the top, an open platform 34.8 metres above the street gives views across the rooftops, spires and towers of the old town.

The observatory is open for telescope viewing on some winter evenings, weather permitting, which is a memorable experience if the sky is clear. Opening hours change between the summer and winter seasons, with longer evening openings on certain days, so check the tower's website before you go. Children under 18 enter free, which makes the tower good value for families. Note that the tower is not included in the Copenhagen Card.

The tower is a listed building without a lift, and it is not well suited to wheelchairs or pushchairs. The ramp is steady but long, so allow around 45 minutes to an hour including time at the top and in the Library Hall. The tower occasionally closes parts of the ramp for maintenance, so check for notices online.

Rundetaarn stands on Købmagergade in the middle of the Latin Quarter, a short walk from Nørreport station and Strøget. The surrounding streets are full of cafés, bookshops and small boutiques, and the old tavern Café Halvvejen is right next door if you want a traditional Danish lunch after your climb.