St David's (Welsh: Tŷddewi) is the smallest city in the United Kingdom, with a population of under 2,000 people. It lies on the River Alun , on Saint David's peninsula in Pembrokeshire, Wales.

The city is built around Saint David's Cathedral, which in the Middle Ages was a popular place of pilgrimage. Next to it, the 14th-century Bishop's Palace is a ruin now in the care of Cadw and open to visitors.

Tradition states that Saint David was born to Saint Non at what is now St Non's , immediately south of the city, in about 500. It is also said that he was baptised at Porthclais, now the city's port, and that he founded the city in around 550.

Other than the cathedral, attractions in the city include the 13th-century Tower Gate , the Celtic Old Cross and an aquarium. St David's is also a popular base for walking and water sports. It has several hotels and a youth hostel, but only one pub.

St David's is the only city in the United Kingdom to lie entirely in a national park, the Pembrokeshire Coast National Park, and it lies near the Pembrokeshire Coast Path.

St David's hosted the National Eisteddfod in 2002.