Pentagon

The Pentagon or Brussels' city centre is the historical city centre of Brussels, Belgium, within the contours of the Small Ring inner ring road. The Small Ring is located on the site of the second walls of Brussels, which were built in the 16th century. As in most European cities, these walls were replaced by large boulevards at the end of the 19th century.

Wikipedia: https://en.wikipedia.org/wiki/Pentagon_(Brussels)

Wikidata: Q18435290