At the northeasternmost edge of the stadium there is a structure identified as a Martyrium. I took two pictures of it, it is not very impressive.

A notice indicates it stems from the 6th century, the Early Byzantine period. It was in the form of a temple, with a burial chamber under the floor. Two columns at the entrance were preserved. On the notice the word martyrium has a question mark, so it seems to be doubted if this identication is correct.