Hourly trains run from Brussels and (on weekdays) Leuven to Nivelles, stopping at Waterloo and Eigenbrakel/Braine-l'Alleud. From either of these stations it is a 3-kilometre walk to the site. The most convenient way to get to Waterloo from Brussels is the hourly bus to Charleroi operated by TEC. It starts at Brussel-Zuid/Midi station and, after about half an hour, has a stop that is just 300 metres away from the Lion's Mound.
Oscar's Bar and Café - Chaussée de Bruxelles 200F, 1410 Waterloo