Sankt Pölten is the capital and largest city of the State of Lower Austria in northeast Austria, with 55,538 inhabitants as of 1 January 2020. St. Pölten is a city with its own statute (or Statutarstadt) and therefore it is both a municipality and a district in the Mostviertel.

The city lies on the Traisen river and is located north of the Alps and south of the Wachau. It is part of the Mostviertel, the southwest region of Lower Austria.

The oldest part of the city is built on the site of the ancient Roman city of Aelium Cetium that existed between the 2nd and the 4th century. In the year 799, it was called Treisma. St Pölten did not become a town until 1050 and officially became a city in 1169. Until 1494 St Pölten was part of the diocese of Passau, and then became the property of the state. A Benedictine monastery was founded in 771. In 1081 it hosted the Augustinian Chorherren and in 1784 their Kollegiatsstift closed. Since 1785, this building has hosted the cathedral of St Pölten. The city replaced Vienna as the capital of Lower Austria with a resolution by the Lower Austrian parliament on 10 July 1986. The Lower Austrian government has been hosted in St Pölten since 1997.

The name St Pölten is derived from Hippolytus of Rome. The city was renamed to Sankt Hippolyt, then St Polyt and finally St Pölten.