This is the longest metal railway structure in Europe. It is 1107 m long and its highest point (above the course of the river Gueule) is 58 m.
It provides a link between the port of Antwerp and southern Germany. It was built in 1915.
None of the Belgian projects had been finalised before the First World War, so it was the German occupiers who launched the process for constructing the Tongre-Aix line under the leadership of General Gröner. This involved completing several large-scale engineering structures, including the Moresnet viaduct, which completely transformed the landscape.
Thousands of workers (+ /- 14,000) from Belgium, Germany, Italy, Hungary, Croatia and Russia were involved in the building operation. The line was opened in 1917. On 18 May 1940, the "Border Cyclists" blew up part of the viaduct but once the municipality had been annexed to the Third Reich, the occupying army rebuilt it.
By 16 December 1940, it was operational again and used for military purposes. Destroyed on 10 September 1944 by the fleeing Germans, it took five years to bring it into service again owing to the shortage of steel.
Almost all freight traffic to Germany travels via the viaduct, which has gradually deteriorated. Its restoration was carried out between 2002 and 2004 (reinforcement of the pillars and replacement of the cross pieces). The line was electrified in 2008.