I had the opportunity visit Christchurch Cathedral in Dublin, Ireland last week. The Cathedral was founded around 1028, improved for centuries, and extensively renovated in the late 1800s. Like other medieval European churches, burials can be found throughout the building and grounds.
The nave of the Church contains the tomb of Richard de Clare, 2nd Earl of Pembroke, better known as "Strongbow," an English lord who participated in the Norman invasion of England. Strongbow died in 1176.
There are also remains underneath the floors;
and in the walls;
and in the crypt.