The 34.8m-high red-brick "Round Tower" has an unusual, spiralling slope (rather than steps) to reach the top. King Christian IV built it in 1642 as an observatory (still in use, as Europe's oldest) as well as a tower for the new university church, Trinitatis. You'll also be following in the hoof-steps of Tsar Peter the Great's horse and, according to legend, the track marks of a car that made its way up the tower's spiral ramp in 1902.
While we can't verify the latter claim, we can attest that the panorama of rooftops and spires from the top is nothing short of inspiring.
The tower still functions as an excellent stargazing platform, making it the oldest functioning observatory in Europe. Visitors wanting to view the galaxy from the 3m-long telescope mounted within the rooftop dome should call ahead to confirm opening times and days, as they vary.
