“Saint David’s Day is the feast day of Saint David, the patron saint of Wales, and falls on 1 March, the date of Saint David’s death in 589 AD. The feast has been regularly celebrated since the canonisation of David in the 12th century, by Pope Callixtus II, though it is not a national holiday in the UK.” Wikipedia
Sorry to use a quote from Wikipedia but it was easier than writing it all out!
St Davids is also the smallest city in Britain. It is in South West Wales. Its somewhere I’ve always meant to visit, but never got there.