St. Stephen's Crypt, Houses of Parliament

In 1834, a fire ravaged the Palace of Westminster, the home of the English Houses of Parliament.

Although the Chapel of St. Mary Undercroft in the crypt survived, it subsequently underwent extensive reconstruction by architect Edward Middleton (E.M.) Barry in order to bring it more in line with the Victorian Gothic style, as well as to return it to its former use as a chapel.

"The Crypt under old St. Stephen's Chapel, Westminster, now in course of restoration" (1859)

The mosaics by Salviati found on the vaulted ceiling displaying floral motifs and heraldry were added between 1860 and 1865.

Sources:
Wikipedia
UK Parliament's flickr Photostream
Antiqua Print Gallery
Lawrence OP's flickr Photostream
Art in Parliament
Guide to the Palace of Westminster. London: Warrington. 1911. 53-54.
Layard, A.H. "Introduction," Paper on Mosaic Decoration read at a meeting of the Royal Institute of British Architects, London: Metchim and Son, 1869. iii.