Houses of Parliament

noun (in Britain)

the building in which the House of Commons and the House of Lords assemble
these two chambers considered together

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012