Visit London (see Tourist Information in Sightseeing) can provide full details on all tour providers in London.

Walking Tours
A variety of guided walks are available from several operators, although the most comprehensive tours are offered by The Original London Walks (tel: (020) 7624 3978; website: www.walks.com). The company also offers themed tours on a huge variety of subjects, including Jack the Ripper and The Beatles. Tours start and finish near a Tube station; there is no need to book and walkers can just turn up at the appropriate station, all of which are listed on the website's timetable. London Mystery Walks (tel: (020) 8526 7755; website: www.tourguides.org.uk) also offers 'Jack the Ripper' tours, as well as ‘Haunted London'. Both take approximately two hours and depart from Aldgate station and St Paul's station respectively.

For the more style-conscious traveller, Urban Gentry Tours (tel: (020) 8149 6253; website: www.urbangentry.com) offers customised private tours that take in the best of London's fashion, design and art. Each tour is tailor-made and gives a fast-track insight into the city.

Alternatively, for self-guided walks, the Silver Jubilee Walkway (website: www.jubileewalkway.com) covers the Thames' South Bank and much of the City and the West End, covering 23km (14 miles) in total.

Bus Tours
Two competing companies offer similar open-top bus tours of London's sights. Tickets are valid for 24 hours and passengers can hop on and off at various attractions en route. The Big Bus Company (tel: (020) 7233 9533; website: www.bigbus.co.uk) offers three different 90-minute sightseeing routes. Original London Sightseeing Tours (tel: (020) 8877 1722; website: www.theoriginaltour.com) also offers various sightseeing bus tours, including a popular ‘Da Vinci Code' route. Golden Tours (tel: 0844 880 6981; website: www.goldentours.co.uk) organises coach tours of the city and day trips outside of London.

Boat Tours
Westminster Pier is the main embarkation point for river trips. From here, there are services east (downstream) or west (upstream). City Cruises (tel: (020) 7740 0400; website: www.citycruises.com) operates sightseeing cruises to Tower Pier (journey time - 30 minutes each way), and Greenwich Pier (journey time - 1 hour each way). City Cruises also offer a Red Rover day pass for its tours, enabling visitors to hop on and off at four different stops.

Going west, summer services by WPSA (tel: (020) 7930 2062; website: www.wpsa.co.uk) depart from Westminster Pier upriver to Kew Gardens, Richmond and Hampton Court. You need to buy tickets before boarding and the journey time is 90 minutes to Kew, and three hours to Hampton Court.

Bateaux London (tel: (020) 7695 1800; website: www.bateauxlondon.com) offers restaurant and cocktail cruises at lunchtimes and evenings. Glass boats with great views of the riverbank leave from Embankment pier. For a less sedate Thames cruise, try London Rib Voyages (tel: (020) 928 8923; website: www.londonribvoyages.com) who offer one-hour trips in small, fast, 12-man ribs setting off from Waterloo Pier. The tours cover all the main riverside sights and include a commentary by a knowledgeable and entertaining guide.

Cycling Tours
The London Bicycle Tour Company (tel: (020) 7928 6838; website: www.londonbicycle.com) offers both relaxed tours along the city's rivers, canals and Royal Parks. The tours are suitable for all levels of cycling ability.

Other Tours
London Duck Tours (tel: (020) 7928 3132; website: www.londonducktours.co.uk) runs unconventional tours on an amphibious craft, which depart from Chichley Street (behind the London Eye) and rumble through London's streets, taking in Whitehall, Trafalgar Square and Buckingham Palace, before plunging into the River Thames for a 30-minute cruise.

London taxi drivers' unsurpassed understanding of the city has been tapped by Black Taxi Tours (tel: (020) 7935 9363; website: www.blacktaxitours.co.uk), London sightseeing tours in a black cab.