William of Hulstbosch (1434-1485) belonged to a family of farmers who had lived in Boondael for a long time. He had a small chapel built in Boondael, at the place called 'Borrestichele'. It was extended in 1474 so that it could accommodate more people. The present-day chapel was the parish church of the hamlet until 1941, when the church of St Adrian was consecrated. Inside, the bricks laid at different times have been exposed and remineralized to prevent them from crumbling. Its current operation is managed by the Ixelles Culture Department. Concerts and exhibitions are held there regularly.