St. James Palace, 11 a.m., the senior detachment of the Queen's Guard forms up before marching to Buckingham Palace.

Buckingham Palace, 11:30 a.m., the new guard marches into the palace court and the ceremony begins.

Whitehall, 11 a.m.(10 a.m. on Sundays), the new guard of the Queen's Life Guard arrives at Horse Guards Arch in Whitehall courtyard.

Tower of London, 11:30 a.m. (except Sundays), guard mounting on Tower Green. A "Ceremony of the Keys" takes place each evening at 9:40. THE TOWER OF LONDON: Open 9:30 a.m. to4 p.m., Monday to Saturdays, November-February; 2 to 5 p.m. Sundays, March-October. Admission is 2 pounds (2.50 July and August) for adults, 1 pound (1.20 July and August) children aged 5-15. Tube station is Tower Hill. TOWER BRIDGE: It's a short stroll from the Tower of London to the city's most famous bridge, and for a small admission charge visitors can take an elevator to the enclosed bridge walkway for a fine view of the Thames; the original control cabin and engine house are open to the public. Open daily 10 a.m. to 6:30 p.m. (April-October); 10 a.m. to 5:30 p.m. (November-March). HOUSES OF PARLIAMENT: Anyone can queue up for admission to the House of Commons on the day of a session, although there is no guarantee of entry and it's wise to write well in advance for free tickets from the American Embassy, which has four passes available daily. (Write to the Protocol Office, American Embassy, Grosvenor Square, London SW1A 1AE.) While it's difficult to gain admission to the prime minister's Question Time, it is somewhat easier to attend the frequent (and frequently lively) question times for other government ministers.

The House of Commons is in session November through July (with periodic recesses), from 2:30 to 10 p.m. Monday through Thursday; after 4 p.m. the public is admitted without tickets whenever there is room in the visitors' gallery. On Fridays, Commons sits from 9:30 a.m. to 2:30 p.m. and the public is admitted without tickets after 10 a.m. if there is room.

No tickets are needed to visit the House of Lords, which sits at 2:30 p.m. on Tuesdays, Wednesdays and some Mondays, 3 p.m. Thursdays, and occasionally at 11 a.m. Fridays. MADAME TUSSAUD'S: Open daily 10 a.m. to 5:30 p.m., closed Christmas. Admission is 2.75 British pounds for adults, 1.55 for children.

Tube station is Baker Street. ST. PAUL'S CATHEDRAL: Open 8 a.m. to 5 p.m. (October to Easter); 8 a.m. to 6 p.m. (Easter to September). Sightseeing not allowed during services. Crypt and galleries open (except Sundays) 10:45 to 3:15 (to 4:15 Easter to October) subject to special services. Small admission for crypt and galleries, and for guided tours 11 a.m. and 2 p.m. Mondays to Saturdays. Services in St. Paul's: Sundays 8, 10:30, 11:30 a.m. and 3:15 p.m.; daily 8 a.m. and 12:30 p.m. (Saturdays 10 a.m.), evensong 4 p.m. (winter), 5 p.m. (summer).

Tube station: St. Paul's. WESTMINSTER ABBEY: Open daily 8 a.m. to 6 p.m. (8 p.m. on Wednesdays) subject to services; on Sundays royal chapels are closed, visitors admitted only to nave and cloisters between services. Daily admission for small charge to choir, transepts and royal chapels, Mondays to Fridays 9 to 4:45 (last ticket 4 p.m.); Saturdays 9 to 2:45 (last ticket 2 p.m.) and 3:45 to 5:45 (last ticket 5 p.m.).

Services in Abbey: Sundays, 8 a.m., 10:30 a.m., 11:40 a.m., 3 p.m. (evensong), 6:30 p.m. (congregational service usually preceded by 30-minute organ recital); Mondays-Fridays, 7:30 and 8 a.m., 12:30 p.m., 5 p.m. (evensong); Saturdays, 8 and 9 a.m., 3 p.m. evensong.

Tube stations: St. James' Park or Westminster.

Check with the British Tourist Authority in London for changes in times or prices.