There have been reports recently of the discovery of the tomb of St Philip the Apostle at the site of the ancient city of Hierapolis in south-west Turkey.
There is a link to an article by Francesco d'Andria, the chief archaeologist on this project, in the journal Biblical Archaeology Review which can be read here. From this the scale of the Martyrium can be appreciated, and one can form some idea of what the whole complex was like.
The remains of the Martyrium of St Philip at Hierapolis
The recently identified tomb of St Philip