The small farming village west of the Brecon Beacons was known as Dyffryn Ceidrich until the 1880s, when it was renamed after its Nonconformist chapel Bethlehem.
Of the 16 places on Earth that share the name, the Carmarthenshire Bethlehem is the smallest - second most-famous. Although quiet for most of the year, in December visitors from all over the UK come to send cards franked with the Bethlehem postmark.
In 1997 Blue Peter's Stuart Miles visited Bethlehem. He met postmaster Gwylam Richards and tried his hand at franking some of the envelopes that had arrived at the local post office.
Today the post office offers a special hand stamp bearing an angel and harp, along with the name of Bethlehem. The building is open part-time for most of the year, but remains open throughout December to cope with demand.
Tens of thousands of letters arrive each year to be reposted around the world with the coveted stamp. A traditional Christmas market is also held in the village for the dozens of tourists who also visit.