Dietrichstein Palace, Baroque revival palace in New Town, Czech Republic.

Dietrichstein Palace, also called Valter Palace, is a neo-baroque building on Voršilská Street in Prague's New Town. Its stucco and sculptural decoration, by Celda Klouček and Jan Kastner, imitates Viennese palaces of the early 18th century, including a portal with half-figures of giants.

The palace grew from a medieval house owned by the Haugvic of Biskupice and Ditrichštejn families. In 1846 the Prague Civic Association (Měšťanská beseda) was founded here with Josef Jungmann and František Palacký present. Sugar manufacturer Matěj Valtera bought it and had architect Bedřich Ohmann rebuild it as a neo-baroque palace, finished in 1891.

The palace's name recalls the Ditrichštejn family, one of its noble owners, and it is also called Valter Palace after sugar manufacturer Matěj Valtera, who had it rebuilt. In 1846 the Prague Civic Association (Měšťanská beseda) was founded here with Josef Jungmann, František Palacký and Pavel Josef Šafařík present.

The palace stands at Voršilská 140/12 in Prague 1's New Town, a short walk from Národní třída and the Národní třída metro stop. It is a working diplomatic mission and not open to the public, so the neo-baroque facade and its giant-figure portal are seen from the street.

The palace is not open to visitors: it has housed the Apostolic Nunciature, the Holy See's diplomatic mission to the Czech Republic, since 1929. The nunciature had previously occupied the Archbishop's Palace at Hradčany from 1919 to 1929.