Sightseeing bus tours are run by several rival companies, their open-top double-deckers setting off every thirty minutes from Victoria station, Trafalgar Square, Piccadilly, and other tourist spots. Tours take roughly ninety minutes (though you can hop on and off as often as you like) and cost around £12. Alternatively, you can hop aboard one of the bright yellow World War II amphibious vehicles used by Frog Tours (tel 20/7928 3132; www.frogtours.com) for a combined bus and boat tour . After fifty minutes driving round the usual sights, you plunge into the river and go on a half-hour cruise. Tours set off every half-hour from behind County Hall, from 10am to dusk, with tickets costing £13. Another money-saving option is to skip the commentary by hopping on a real London bus - the #11 from Victoria will take you past Westminster Abbey, the Houses of Parliament, up Whitehall, round Trafalgar Square, along the Strand and on to St Paul's Cathedral.

Walking tours are infinitely more appealing, mixing solid historical facts with juicy anecdotes in the company of a local specialist. Walks on offer range from a literary pub crawl round Bloomsbury to a tour of places associated with the Beatles. Tours tend to cost £4-5 and usually take two hours. To find out what's on offer for the week, check in the "Around Town" section of Time Out. The widest range of walks on offer are run by Original London (tel 020/7624 3978).