Begin your tour with one of the country's most potent icons, where most of England's kings and queens have been crowned. Aim to get here when it opens at 9:30am, before the crowds descend.
As you emerge from Westminster Abbey, you confront the symbol of the nation's political power:
The Houses of Parliament & "Big Ben"
Gaining admission to the debating chambers requires a long wait, which 1-day visitors will have to forgo, but you can admire the massive Gothic Revival pile from the outside.
Walk north along Whitehall until you reach:
No. 10 Downing Street
Bear left and look down Downing Street to No. 10. Security concerns mean that it's no longer possible to walk to the prime minister's front door.
Continue north on Whitehall to its end at:
Trafalgar Square
The hub of London, this is Britain's most famous square and the scene of many a public demonstration.
Pass through Admiralty Arch in the square's western corner, and down the Mall to:
Buckingham Palace
If you're not on a 1-day schedule, you can take a look around during the brief summer opening.
Changing of the Guard
Time it right to catch the Changing of the Guard ceremony — it's at 11:30am. However, you'll have to leave after a few minutes if you're sticking to the 1-day schedule.
Retrace your steps to Trafalgar Square, with a detour into adjacent:
St. James's Park
Make your way back to Trafalgar Square via a stroll through one of London's most elegant green spaces.
On the north side of the square, you can enter the:
National Gallery
The galleries cover some 8 centuries of the finest art ever created. Even on the most rushed of schedules, try to set aside at least 1 hour.
Head north along Charing Cross Road, and then take a left into:
Leicester Square
Make for the "tkts" booth in the center, where you can book reduced-priced tickets for one of this evening's West End shows.
Retrace your steps to Trafalgar Square:
Take a Break — Café in the Crypt
Stop off for lunch at the atmospheric subterranean self-service dining room in St. Martin-in-the-Fields Church, 6 St. Martin's Place, WC2 (tel. 020/7839-4342) on the eastern edge of the square.
Suitably fortified, head east along the Strand, past the Savoy Hotel and Theatre as far as Waterloo Bridge and:
Somerset House
Those spreading things over several days can visit the Courtauld Gallery and Embankment Galleries. If you're watching the clock, content yourself with a quick glimpse of the magnificent courtyard.
Head back west along the Strand, and then up Southampton Street to:
Covent Garden
If you have the time, enjoy the street performers on the Piazza, a rummage at the market, a mooch about St. Paul's Church, and a tour of the London Transport Museum. Or, if you're on a tighter schedule, choose just one of the above.
Head north, up James Street, and take the Piccadilly Line northbound one stop to Holborn. Change to the Central Line and head east two stops to:
St. Paul's Cathedral
Get climbing, up 500 or so steps to enjoy the panoramic sweep from the top of the dome.
Millennium Bridge & River Thames
This is a bit of a detour, and so is only realistic for those spreading the tour over more than 1 day. Head south from the cathedral courtyard to the pedestrian bridge crossing the River Thames.
Cross the bridge and you'll find yourself at:
Tate Modern
A tour of London's premier museum of modern art should be undertaken only by those with time to spare.
Retrace your steps to St. Paul's Churchyard:
Routemaster Bus
Just outside the cathedral, you can board one of the great moving icons of London, the 15H, a shiny red, open-backed Routemaster bus, which runs every 15 minutes as part of a heritage service.
It's a 10- to 15-minute journey to the:
Tower of London
Time it to arrive at this 900-year-old symbol of royalty, blood, and gore late in the afternoon, when some of the hordes have departed. Allow yourself a few hours to get your money's worth — it is pretty expensive.
Tower Bridge
Once the Tower shuts, head east for a stroll south across London's iconic bridge.
Take a Break — Dickens Inn
At the bridge's northern end, on the eastern side, end your sightseeing day with a pint at the Dickens Inn, Marble Quay, St. Katharine's Way, E1 (tel. 020/7488-2208), housed in a restored warehouse in St. Katharine's Dock. There's a pizza restaurant on the second floor for a quick bite.
Take the Tube from Tower Hill to Bank. Change to the Central Line, alight at Tottenham Court Road and you'll be back in the heart of the West End for:
A Night at a London Theatre
Bring things to a close with a night out in the West End, making use of those tickets you picked up earlier.