Open today from 10-21
The observatory 18-21
Plan of the Round Tower

Measure and Weight

How long is the Spiral Ramp? How much does the Round Tower weigh? How large is the Library Hall? Get the answers to these questions and learn much more about the measure and weight of the Round Tower here.

Plan of the Round Tower

Height of the Tower

Street to platform: 34.8 m

The Spiral Ramp

Turns: 7.3 (today)
(originally 7.8 (today under the wooden staircase)
Outher length: 281 m (originally 300 m)
Innter length: 93.5 m (originally 100 m)
Outer gradient: 10 %
Inner gradient: 33 %
Elevation per turn: 3.74 m
Centre to the outer wall of the core: 195 cm
Centre to the inner wall of the outer wall: 610 cm
Radius: 768 cm

The Library Hall

Floor-to-ceiling height: 3,85 m
Area: 811 m²
Volume: 3121.5 m³
Weight of the air in the hall: 3.758 t

Staircases

Wooden staircase: 28 steps
Stone staircase: 31 steps

The Observatory

Height: 7 m
Radius: 3 m

The Platform

Area: 104.5 m²

More curious information

12° 34′ 32.25″ East
55° 40′ 52.81″ North
Weight: 5914 t
(density of fired clay + bricks: c. 2 t/m³)