The Round Tower

Commissioned by King Christian IV in the early 17th century, the Round Tower (Rundetårn) was built as the first part of the Trinitatis Complex, which aimed to provide scholars with an observatory, a church, and a library. Completed in 1642, the tower was intended to continue the astronomical legacy of Tycho Brahe, whose work was fundamental to the scientific revolution. Standing at 36 meters tall, it represents the golden age of Danish architecture and scientific ambition during a period when Denmark was a major European power. What truly sets the Round Tower apart is its unique spiral ramp instead of stairs. This 209-meter-long paved path winds seven and a half times around the hollow core of the building. The design was purely functional, allowing heavy astronomical instruments and books for the university library to be transported via horse-drawn carriage. Over the centuries, this ramp has seen many famous visitors, including Peter the Great, who famously rode his horse to the summit in 1716 followed by his wife in a carriage. Although the university moved its primary astronomical research to a new facility in 1861, the Round Tower remains the oldest functioning observatory in Europe. It underwent significant restoration in the 20th century to preserve its masonry and the iconic observatory at the top. Today, it serves as a cultural hub, hosting exhibitions in the old Library Hall and offering amateur astronomers a chance to peer through its telescopes during the winter months while providing tourists with one of the best views of Copenhagen.