Pembrokeshire is the fifth-largest county in Wales, but has more scheduled monuments (526) than any except Powys. This gives it an extremely high density of monuments, with 33.4 per 100 km2. (Only the tiny county boroughs of Newport and have a higher density). With three-quarters of its boundary being coastline, Pembrokeshire occupies the western end of the West Wales peninsula, terminating with the tiny cathedral city of St David's. It was a historic county in its own right but between 1975 and 1996 it joined Carmarthen and Ceredigion in the much larger county of Dyfed.