In the course of Europe's rearrangement after Napoleon's end in 1818, October 18th Aachen became summit meeting place of the monarchs from Prussia, Austria and Russia, the so called "monarch-congress". It was the 5th annual of Leipzig nation's battle. At the convention's end they renewed their pledge of Leipzig to act in future "for all nation's salvation to establish order and truth". It was performed at the Adalbertsteinweg, about the place of today justice-center.
The congress-memorial is recollecting an extraordinary meeting, that it was for that ancient time. It's realisation delayed for many years and was accomplished in 1844. First the memorial was located at the pledge's place, was demounted for a city-extension in 1914, stored and finally rebuild in the cure-park in 1928.
Although he didn't lived to see and did not take part in detailing the memorial-design is done by Karl Friedrich Schinkel: His abatement contains a drawing of it. The memorial is classified as the only pure Aachen-building of him. For his both other local ones, city-theatre and Elisen-fountain, this cannot be sayed.
In 2018 the building, especially its steel-made roof-substructure is in enormous need of rehabilitation. In addition most of its blue-stone floor-slabs are broken and have to be repaired. The still existing Second World War bullet holes will be preserved. My photogrammetry got the task to show the current condition for a qualified craftsman order.