On 15 July 2005, the geodetic arch created at the initiative of F.G.W. Struve, an astronomer from the University of Tartu, which was a meridian section for measuring the shape and size of the Earth between 1816–1855, was entered into the list of UNESCO World Heritage. The 2,820 km arch reaches from Northern Norway to the Black Sea. 34 of the original measuring points are known to exist; three of those are located in Estonia. In Tartu, the part of UNESCO World Heritage belonging to Struve meridian arch is the Tartu observatory. A plaque indicating the location of the arch is located outside the Observatory.