For ROMAN London, we start in St. Alphage Garden, close to London Wall, where a fine section of Roman and medieval city wall remains. A large inscribed tablet marks the spot.
Medieval Head west via London Wall and Little Britain for St Bartholomew the Great, London's oldest church, founded as a priory in 1123. William Hogarth was christened here.
Walk round the corner to the junction of Giltspur Street and Cock Lane (toilets nearby). Here an inscription and a cherub - the Golden Boy of Pye Corner - mark where the Great Fire "occasion'd by the sin of gluttony" ceased.
Backtrack to St Botolph's churchyard, a good place for a break. The Victorian obsession with death can be seen on a wall recording acts of heroism. "Walter Peart, driver; Harry Dean, fireman, of the Windsor express 18th July 1898. Whilst being scalded and burnt, sacrificed their lives in saving the train."
Back east via Gresham Street to the 15th Century Guildhall, the City's seat of government. The stunning Great Hall has witnessed state celebrations, the trial of Lady Jane Grey and the Blitz. The medieval crypt is London's largest.
1500 - 1800 South of the Guildhall, off Cheapside, the church of St Mary-le-Bow is better known as Bow Bells. All Cockneys are born within their sound. Severely bombed during the war, the spire is the only part of Wren's 1673 church to remain. Look out for the model inside of London immediately after the Great Fire.
Via Bow Lane turn left for Queen Victoria Street and the remains of the Roman Temple of Mithras, discovered when the adjacent office block was built.
Turn into Walbrook for the City's finest church, St Stephen Walbrook, easily missed. Wren used it as a "dummy run" for St Paul's Cathedral. The magnificent dome is best seen from inside.
From Walbrook turn left into Cannon Street. Opposite the station, in front of the Overseas Chinese Banking Corporation, is the London Stone. Its age and history are unknown, but it was possibly a Roman milestone - "point zero" in Britain.
Cross the road and make for College Hill. A plaque on the left marks the site of Dick Whittington's house. He is buried in the adjacent church of St Michael Paternoster Royal, where Dick and his cat are depicted in stained glass.
Victorian Return east along Upper Thames Street. Cross over and look for the sign marked "Thames Path East" by the fire station. This leads to the riverside, a good place for a break, and Fishmongers' Hall. The Fishmongers' livery company has been here since 1434. A few hundred yards downstream is the site of the old Billingsgate fish market. Enjoy the view across the river: Southwark Cathedral and the stark brick chimney of Bankside Power Station, now the Tate Modern. Then walk under London Bridge, immediately ascend the steps and make for Gracechurch Street (toilets nearby). Bull's Head Passage, on the right, leads to Leadenhall Market: the elegant glass and ironwork roof is Victorian, although meat and poultry have been sold here for centuries. Exit the east side for a close-up view of the new Lloyds building.
Continue east to Fenchurch Street station, the City's first rail terminus in 1841. Turn south, down the steps for Seething Lane.
The church of St Olave, from 1450, is one of few not consumed by the Great Fire. Dickens called it St Ghastly Grim, for the stone skulls above the churchyard entrance. Mother Goose and Samuel Pepys are buried here. A plaque opposite records the Navy Office where Pepys worked.
Twentieth Century The route now passes beyond the City boundaries, south to Trinity Square Gardens, a good place for a break. Here, the poignant Mercantile Marine Memorials record the 36,000 names of those in the merchant navy and fishing fleets who lost their lives during two World Wars, and have no grave but the sea. Look for the long Lusitania listing on the southern columns of the Great War memorial.
Cross the road and follow the lower footpath along the Tower of London's northern periphery. This leads to St Katherine's Dock, designed by Thomas Telford in 1828. At the Western end of Docklands, it is now a marina surrounded by luxury dwellings. It's a fine symbol of late 20th century regeneration and a delightful place to rest your aching feet.
What you need to know Start: Moorgate or Barbican tube. Finish: Tower Hill tube. Distance: about three miles, mostly level walking. Time: Three hours, longer to explore buildings in depth.
Travel tips The City becomes very crowded at lunch time, so it is easier to get around in small groups. Many churches hold lunch time services or lectures and most close at weekends. Take a good street map. St Bartholomew the Great is closed on Mondays.The Great Hall is occasionally closed for functions. Check on 020 7606 3030 ext 1463. City information : 020 7332 1456. Web: www.cityoflondon.gov.uk