Houses of Parliament (Great Britain) Fast Facts

 The Houses of Parliament and the river Thames are shrouded in early morning fog on January 21, 2014 in London, England.

(CNN)Here's some background information about Great Britain's Houses of Parliament, located on the Thames River in London.

The meeting place of Great Britain's bicameral legislature - composed of the House of Commons and the House of Lords - is also known as Westminster Palace.
    Security technology, such as CCTV cameras and alarms, are used throughout the estate.
    In addition to unarmed security officers, armed police officers are also on the premises.
    11th century -
    The original palace is built.
    1604 -1605 - A group of English Catholics, including Guy Fawkes, plots to blow up Parliament to protest their treatment by the Protestants. However, the plot is uncovered and the conspirators hanged. November 5 is still celebrated in England as "Guy Fawkes Day", when people celebrate with bonfires and fireworks and burn effigies of Fawkes.
    October 16, 1834 - A fire destroys most of the building.
    1840 - Construction begins on the current Houses of Parliament.
    1852 - House of Commons first used.
    1870 - Construction completed.
    May 11, 1941 - House of Commons chamber destroyed in bombings during WWII. It is rebuilt by architect Sir Giles Gilbert Scott.
    1950 - The reconstruction of House of Commons is complete.
    1987 - The United Nations Educational, Scientific and Cultural Organization (UNESCO) designates the building as a World Heritage site.
    2000 - Portcullis House, a new Parliamentary building, is completed.
    February 2001 - Portcullis House officially opens.
    June 18, 2015 - An independent committee issues a report outlining the need for extensive repairs throughout the historic complex. Issues that need attention include wiring problems, loose asbestos and rats. The principal architect at the Houses of Parliament tells the BBC, "Some of the facades are actually sinking and we're going to have to investigate that very soon."
    March 22, 2017 - Khalid Masood plows a car through crowds on Westminster Bridge in central London before attempting to storm the Houses of Parliament in what police believe was an act of Islamist-inspired terrorism. Four people, including a police officer, are killed and scores injured before he is shot dead by police.
    Designers/Architects - Sir Charles Barry along with Augustus Welby Pugin. Barry won a competition to be the architect.
    There are four floors:
    - Ground floor - Offices, river front houses, meeting rooms, and dining halls.
    - First floor - More dining rooms, Chambers of the House of Commons and House of Lords, and libraries.
    - Second floor and Third floor - Committee rooms.
    One end of the palace holds a private area for the speaker and on the other end, an area for the lord chancellor.
    Made of limestone with an iron roof.
    Three large towers, the Elizabeth Tower (316 ft. tall, holds the bell Big Ben), Victoria Tower (323 ft.), and Central tower (300 ft.)
    The main entrance is called St. Stephen's Hall, which leads immediately to the Central Lobby, or Octagon Hall. This area is open to the public.
    Parliament has taken over nearby buildings as the need arose, including the Parliament Street Buildings and the Norman Shaw North and South buildings.