A heavenly view of Aachen and the surrounding area opens up from the summit plateau of the Lousberg. Look out over the landscape, from the Soers valley to the Tivoli and the Aachener Wald forest and the Eifel foothills. This is precisely what the geographer Jean Joseph Tranchot did in 1807, when he recorded the entire region on a map. The great blue stone obelisk was erected here for this purpose and for other astronomical observations.