Travel UK: Wide open spaces of WC1

For some people, "suburban" is now synonymous with respectability. But that is not how the suburbs started: on the contrary, they stood for unbridled freedom outside the city walls, beyond reach of the earliest bylaws.

Holborn was London's first suburb. Its secret precincts are a treasure trove for the urban traveller who wants to dig up masterpieces from the 13th to the 19th centuries. Given the amount of bomb damage and the cut- price quality of most rebuilding, it is remarkable how much has survived.

Arm yourself with a few good maps: Morden's of 1677, Rocq's of 1756 and Harwood's of 1799 are the best (you can study them in the Maps and Prints Room of the Guildhall Library; take a pencil for notes - they will swoop on you if they see a pen).

Holborn itself was the main road westwards from the City. Where the ornate Victorian viaduct now leads into the City on a level plane, there was the steep valley of the river Fleet (otherwise known as the Holeburne) and the switchback of Snow Hill. A village church still stands on either side: St Andrew, which survived the Great Fire only to be rebuilt by Wren in 1706, and St Sepulchre which is still a fine 15th-century church.

There are shops and offices all around but there is one glorious clue as to what lies behind: just above the entrance to Chancery Lane station, on the south side, there is an outburst of Elizabethan half-timbering. An unobtrusive alleyway under it leads to a Georgian courtyard with a toy-like Elizabethan dining hall, sensitively rescued after war damage. This is Staple Inn, originally established in the Middle Ages as one of the small Inns of Chancery, and a satellite of the much grander Gray's Inn.

Around the corner, in Chancery Lane, is Lincoln's Inn, which started life as the Earl of Lincoln's house and characteristically turns its back to the street except for the gatehouse of patterned brick built in 1518. Behind it is the best of these collegiate precincts: a Tudor courtyard with hall and chapel, ironed out a bit in an unfortunate Sixties reconstruction, and the magnificent New Square, spec-built barristers' chambers of 1685. Beyond is the big square of Lincoln's Inn Fields; the best surviving mansion is the brilliant and eccentric museum-house of the architect, Sir John Soane.

Behind the main roads, Holborn is a network of medieval precincts of varying degrees of secrecy, interspersed with the brick houses of City gents keen to move out after the Great Fire. Next to Staple Inn, Dyers Buildings was carved into the backland as a tiny Victorian gorge with brown brick Gothic cliff faces.

Dominating the scene from the north side is the stupendous pile of the Prudential, put together from 1879 by the architect Alfred Waterhouse. It was built on the site of another legal precinct, Furnivals Inn, where Dickens lodged, and a recent enlightened reconstruction has opened up its main passages and courtyard to the public as a thoroughfare on weekdays.

The Pru's left-hand end flanks Brooke Street, driven through on the site of the town house of Fulke Greville, Lord Brooke, James I's Chancellor of the Exchequer. He was killed here by a servant denied a pay rise. The site of its gardens forms the tree-shaded open space of Brookes Market; the actual market is now in Leather Lane and resists all attempts to civilise it. Brookes Market is overlooked by another Victorian gem, William Butterfield's clergy house of St Alban. The saddlebacked church of St Alban's itself was a hotbed of High Church Anglican radicalism in the late-19th-century slums, providing a kind of embryo welfare state with infant nursery, soup kitchen, blanket- loan society, and more.

Behind St Alban's there is the splendid Bourne estate of 1903, built on the site of Meux's brewery. It faces Clerkenwell Road, which until the 1860s was called Liquorpond Street, no doubt because of the prevalence of brewing; it became the centre of London's Italian community with their elaborate church of St Peter. In its narrow porch is surely London's most tragic memorial: a bronze of desperate hands reaching out of the sea. It is a memorial to the single greatest loss of London civilian lives in the war: the sinking of the Arandora Star off the coast of Ireland. It was transporting more than 1,000 Italian children to Canada as enemy aliens.

It is sobering to look across to the top of Hatton Garden, where a blue plaque proudly records that here, in the 1870s, the young Sir Hiram Maxim invented the machine-gun.

This brings us to the largest of Holborn's precincts: Hatton Garden. Here, almost everything has been converted or rebuilt by the jewellery trade into hundreds of little shops. Back in the Middle Ages, the garden was that of Sir Christopher Hatton, Lord Chancellor, on whose behalf Queen Elizabeth forcibly extracted a lease on most of the Bishop of Ely's Holborn palace.

Between numbers 8 and 9 Hatton Garden, next to the bookies, is an arched passage to London's most obscurely sited pub, The Mitre, "founded 1546," it says. Beyond is Ely Place, a Georgian private street, complete with gates and a watch house for a uniformed flunkey. It was laid out by the surveyor Charles Cole in 1773, after local citizens objected to the Fleet Prison being resited there - an act of nimbyism which had one precious result, the preservation of the Bishop's chapel, now the Roman Catholic parish church of St Etheldreda. Here, the brilliant upper room of the 1290s, with its graceful window tracery, has the simplicity of all great architecture.