Finished in 1157, The Basilica of the Holy Blood (Heilig-Bloedbasiliek, Basilique du Saint-Sang) in Bruges is located in Burg square. It is said to contain the blood of Jesus. Entry to the church is free but entry into the church musuem will cost you €2. You’ll want to plan ahead by seeing the visitation hours here: http://www.holyblood.com/?page_id=96&lang=en
If you haven’t booked a hotel in Bruges, the Grand Hotel Casselbergh hotel is in Burg square. It’s BelgiumPlan recommended.