Caer Caradoc to the west of GZ, is one of the most important locations in all of ancient British history. It is the fabled fortress city of King Caradoc 1, son of Arch, who fought the Romans from 42-51AD.
There is a clearly defined pentagon shaped walled city that was spotted in the last decade with the help of Google maps.
Historical references to Caer Caradoc are many and include statements in the Brut Tyssilio (684 AD) and the later Gruffyd ap Arthur (1135 AD) where Merddyn Emrys (Martin Ambrosius) and his mother are said to have met with the Ambassdors of Vortigern at St. Peter's Super-Montem Church at Caer Caradoc, where they lived.
NOTE: Caer Caradoc is on private land. Permission must be sought from the landowner if you wish to go inside the perimeter.