The Martyrion of Karpos and Papylos is a substructure located underneath the Church of St. Menas in the region of Psamathia (Turkish Samatya) in Constantinople, not far from the Monastery of Peribleptos. It was situated on the Mese leading to the Golden Gate, not too far from the sea walls. 

According to tradition, St. Helena, the mother of Constantine I, ordered the building of this martyrion built and dedicated to the saints Karpos and Papylos. Though its identity and date are uncertain, it has traditionally been identity as the Martyrion of Karpos and Papylos and dated to the 4th or 5th century. Later there was another church on the location, the domed St. Polykarpos, which was destroyed in a fire in 1782. The current church on location, Hagios Menas, was built over the substructure in 1833.  
The substructure is relatively well preserved. The substructure contains an apse and has a domed vault made of brick. It is partially surrounded by a barrel vaulted passage. It is currently the restaurant Helena Çak Stones. It has another entrance at the car wash located next to it.