The square is actually a marvellous little garden with 48 bronze statuettes. It's not far from the busy city centre and yet it is peaceful and quiet. In the surrounding area, there are several cafés and some places to get food (e.g. chocolatiers and bakeries) which you can then peacefully enjoy while sitting in the park.
Note the fountain of Counts of Egmont and Horn standing in the centre of the square. Egmont and Horn were important figures of resistance against the Spanish tyranny and their execution led to public protests that eventually resulted in the independence of the country.
Wikipedia http://en.wikipedia.org/wiki/Sablon_(Brussels)#Petit_Sablon
Official Website https://www.environment.brussels/fiche/petit-sablon-square
Address 15 Kleine Zavel, Brussel 1000, Belgium
Coordinates 50°50'22.212" N 4°21'23.694" E