Caerphilly is a town in the county borough (or principal area) of Caerphilly (principal area) in south Wales. It is located at the southern end of the Rhymney Valley. At the time of the 2011 UK census the town had a population of 15,214. It is a commuter town of Cardiff and Newport, which are located some 7.5 miles (12 km) and 12 miles (19 km) away, respectively. It is separated from the Cardiff suburbs of Lisvane and Rhiwbina by Caerphilly mountain. It is traditionally within the county of Glamorgan, on the border with Monmouthshire and it is the largest town in the county borough (or principal area) of Caerphilly, which since 2003 has formed part of the lieutenancy area of Gwent. The town gives its name to Caerphilly cheese, which originated in the area.
The first three maps are provided by A Vision of Britain through Time
These maps were found on Wikimedia Commons
These maps of Glamorgan post-1974 were found on another site and are very useful for sorting out the up-to-date geography of the area