The Chapel of St Mary Undercroft in the heart of the Palace of Westminster, home of the UK Parliament, was completed by King Edward I in 1297, further developed under Edward II, and finally completed by Edward III in around 1365. Built to imitate the splendour of the Sainte Chapelle in Paris, the undercroft chapel is a rare survivor of the lower storey of a two storey chapel, originally dedicated to St Stephen and was one of the few structures in the Palace of Westminster to survive the great fire of 1834, although much of its stonework was harmed.
The chapel was heavily restored between 1860 and 1870 and contains five vaulted bays and clustered columns of polished Purbeck marble. It is a Royal Peculiar, which means it does not come under the jurisdiction of a bishop but is under the monarch's control. The monarch exercises this via the Lord Great Chamberlain.
The baptismal front was designed by Edward M Barry during the refurbishment in the 1860s. Its bowl is made of alabaster and the cover is surmounted by a brass statue of St John the Baptist, who is also depicted on the Baptistry’s wall paintings.