THE HOUSES OF PARLIAMENT

The Houses of Parliament or the Palace of Westminster is the seat of the British Parliament. It includes the House of Lords, the House of Commons, Westminster Hall, the Clock Tower, the Victoria Tower, various committee rooms, residences, offices, etc.
The famous Clock Tower houses "Big Ben" - the clock named after Sir Benjamin Hall under whose direction the construction of the clock was conducted. People call the clock Big Ben, but the name really belongs to the bell on which the clock strikes the hours. A light at the top of the Clock Tower shows when Parliament is sitting at night.
The British flag flying from the Victoria Tower shows that the Parliament is in session.