Brussels

Beside the Beurs (Bourse) - Brussels Stock Exchange - were these ruins (behind glass). "In 1238, a Franciscan convent is set up on the banks of the Senne river, right next to Saint Nicolas church. The discovery of the ruins was in 1988 when the Bourse was being renovated. Notably, this archeological site was the location of Duke Jean the First of Brabant’s tomb, who died in 1294"