"Round Tower"

(Rundetaarn) Copenhagen
The Rundetårn (historical spelling: Rundetaarn; Danish for "Round Tower") is an astronomical tower located in the city center of Copenhagen. Today, the Rundetårn is a well-known tourist attraction, a public observatory, and an exhibition venue, while its roof serves as a popular observation deck. King Christian IV commissioned its construction between 1637 and 1642, based on designs by the architect Hans van Steenwinckel the Younger. It is connected to the old University Library and the Trinity Church, both of which were built in the decades following the tower's completion. The circular tower has a diameter of approximately 15 meters and stands 34.8 meters tall. With the exception of the final few meters leading from the observation deck to the observatory, the tower is ascended not via stairs, but via a 209-meter-long spiral ramp that winds around the tower's central core in seven and a half full turns. This 4-meter-wide ramp was designed to allow books, instruments, and similar items to be transported up the tower by horse-drawn carriage. Quote: Wikipedia