| Rundetaarn | |
|---|---|
 | |
  Location within Copenhagen | |
| Former names | Stellaburgis Hafniens |
| General information | |
| Architectural style | Dutch Baroque |
| Construction started | 1637 |
| Completed | 1642 |
| Client | Christian IV of Denmark |
| Design and construction | |
| Architect(s) | Hans van Steenwinckel the Younger |
The Round Tower (Danish: Rundetårn) is a 17th-century tower in Copenhagen, Denmark, one of the many architectural projects of Christian IV. Built as an astronomical observatory, it is noted for its equestrian staircase, a 7.5-turn helical corridor leading to the platform at the top (34.8 meters above ground), and its views over Copenhagen.
The tower is part of the Trinitatis Complex which also includes a chapel, the Trinitatis Church, and an academic library, which were the first facilities of the Copenhagen University Library founded in 1482.