Denmark’s point zero

Copperingraving showing the theteodolite used in the mapping.of Danmark.

Copperingraving showing the the teodolite used in the mapping of Danmark.

When you step onto the glass plate in the hollow core of the Round Tower, your feet straddle Denmark’s point zero.

Late in the 1760s, astronomer Thomas Bugge was commissioned to survey Denmark and draw a new and more accurate map of the kingdom. The plan was to divide the country into a series of triangles* and determine distances by measuring the angles and one side. The first triangle was drawn between the Round Tower, Brøndbyhøj and Tinghøj in Gladsaxe, where the terrain was flat and easy to measure. This meant that the Round Tower was the zero point (0,0 degrees of longitude and latitude), the starting point for the calculations.

The King appointed a number of surveyors, who spent the summer taking measurements and the winter in training in the Round Tower, where the University of Copenhagen’s astronomers measured both the Earth and the universe.
The surveyors’ measurements formed the basis for the first accurate map of Denmark, which was published in 1841.

* Triangulation