The story
Welcome to one of the most iconic silhouettes in the Copenhagen skyline. As you stand here on Købmagergade, looking up at the warm red and yellow brickwork of the Rundetaarn, or Round Tower, you are looking at a 17th-century marvel of functional design. Built by the famous architect-king Christian IV and completed in 1642, this tower was part of the Trinitatis Complex, a unique triple-threat of architecture that combined a church, a library, and an observatory all in one footprint.
But as you begin your ascent, you will notice the tower’s most famous quirk: there are no stairs. Instead, a wide, whitewashed spiral ramp winds its way upward, circling the hollow core seven and a half times. You might wonder why a king would choose such a peculiar design.
The answer is grounded in pure logistics. Christian IV was a practical man. He knew that the scholars and astronomers using the tower would need to move heavy, delicate equipment—massive brass globes, telescopes, and thousands of heavy, leather-bound books—up to the library and the observatory at the top.
A staircase would have been a nightmare for porters, so the king built a ramp. This allowed horses and carts to haul the heavy loads directly to the upper floors, essentially creating a 17th-century service elevator. This leads us to the tower’s most legendary moment.
In 1716, during the Great Northern War, Copenhagen played host to a visitor who was truly larger than life: Tsar Peter the Great of Russia. Peter was a man of immense curiosity and very little patience for traditional decorum. During a visit to the tower, he decided to put the ramp’s functionality to the ultimate test.
To the absolute shock of the Danish royal court, the Tsar didn’t walk; he mounted his horse and galloped all the way to the top of the 209-meter-long ramp. Not to be outdone, his wife, Empress Catherine, reportedly followed him in a grand carriage drawn by six horses. Imagine the deafening thunder of hooves echoing against these thick stone walls and the smell of horsehair and leather filling the scholarly silence of the library hall.
As you make your own way up today, notice the light pouring through the tall windows and the occasional niches where you can see the tower’s hollow core. When you finally reach the outdoor platform, you will find yourself at the oldest functioning observatory in Europe. Take a breath and look out over the sea of copper-green spires and orange tiled roofs.
You are standing where science, royalty, and a bit of Russian bravado once collided.