Bangor is the name of several places in Wales, Ireland and the USA (and possibly elsewhere).
One of the smallest cities in the UK is Bangor in Gwynedd, North Wales. It is a university town and has a population of roughly 20,000 of whom about a third are students. The origins of the city date back to the founding of a cathedral by the Celtic saint Deiniol in the 7th century AD (or thereabouts). The name 'bangor' itself comes from a Welsh word for a type of fenced-in enclosure, such as was originally on the site of the cathedral. The present cathedral is a somewhat more recent building and has been extensively modified throughout the centuries. While the building itself isn't the oldest, and certainly not the biggest, the bishopric of Bangor is one of the oldest in the UK. Another claim to fame is that Bangor allegedly has the longest High Street in Europe.
Also in North Wales, but close to the English border, is the somewhat smaller Bangor-Is-Y-Coed (which literally means Bangor Below The Trees, but in English is usually called Bangor-On-Dee).
There is a town called Bangor in Northern Ireland, not far from Belfast, and another one in the state of Maine in the USA. Bangor, Maine is known as the town where many Stephen King stories take place.