Llanwrtyd Wells is a small town in Powys, mid-Wales, on the River Irfon.
With a population of 850 (United Kingdom Census 2011), Llanwrtyd Wells is renowned for being the smallest town in Britain.
The town is on the A483 between Llandovery and Builth Wells and is located near the pass between the Tywi and Irfon valleys.
Llanwrtyd Wells grew as a spa town around the Ffynnon Ddrewllyd ("stinking well" because of the strong smell of hydrogen sulphide), which still exists. The town was also known as an eisteddfod site, and is the site of both the World Bog Snorkelling Championships and the annual Man versus Horse Marathon, as well as other annual events.
The fashion for spas reached its peak in the Victorian Era and many of the hotels in the town date back to that time. The Belle Vue Hotel, the only purpose-built hotel in Llanwrtyd, was built in 1843.
Llanwrtyd Wells had two golf clubs and courses during the 20th century, both are now defunct.
In contrast to its past history as a spa town, when hundreds flocked to take the waters for their claimed medicinal effects, the area is now better known for recreations such as pony trekking, mountain biking, walking and birdwatching, and for its annual Man versus Horse Marathon, Beer Festivals and World Bog Snorkelling Championship.
Llanwrtyd Wells is Twinned with Meriel, France and Cesky Krumlov, Czech Republic.