The characteristic curves of the River Thames have defined the shape of London. The sprawling capital that we know now has evolved from the villages that grew up around the Thames - places where ships could be built and moored, or where the river could be bridged and defended.

It is easy to forget that London grew up as a waterside city, with its oldest buildings never far from the shore. And despite the ravages of war, time and redevelopment, you’ll still find many curious and ancient buildings along the banks of the Thames, often hidden away and somehow adrift from the modern city. A selection of these historic buildings - stretching from Kew in the west to Greenwich in the east - are now at the centre of a year-long festival, the London String of Pearls, which is making a collective display of 67 public and private buildings and institutions, some not previously opened to visitors, others offering special exhibitions.

Among the buildings opening especially for the festival will be Lambeth Palace, the London stronghold of the archbishops of Canterbury since the 12th century. The building has been added to and altered according to the fashions of the intervening centuries. Major additions include a 13th-century chapel, the Tudor gatehouse and a 19th-century neo-Gothic facelift. From April, visitors will be able to look around sections of the palace, including its historic library, the crypt and guard room. There will also be an exhibition of written and art work about Lambeth Palace, called Picture This, produced by children from a local primary school.

Another “pearl” opening for the festival will be the Shipwright’s Palace in Deptford. This Tudor building, due to be restored and opened to the public by April, will celebrate the era of the great seafaring explorers and raiders of the 16th and 17th century. Although its billing as “the Cape Canaveral of its day” might sound a little over enthusiastic, it was from the dockyard at Deptford that adventurers such as Sir Francis Drake and Sir Walter Raleigh sailed to the “new world”.

There are also a number of more limited openings of “public” buildings which are usually inaccessible, such as the Custom House, Southwark, which is still the headquarters of the customs and excise service, the Foreign and Commonwealth Office, in Whitehall, and Westminster Hall, within the Houses of Parliament, all of which will have open days and exhibitions through the year. And as well as conventionally historic buildings, the festival includes access to culturally significant sites, such as Bush House, headquarters of the BBC World Service, and the nearby London School of Economics.

The Fishmongers’ Hall near London Bridge is to be opened to the public on selected days over the summer. This might sound as dull as, well, fishwater, but there has been a Fishmongers’ Hall on the present site since 1310 - a reminder of how long and continuous the history of such institutions can be. The present Hall was built between 1831 and 1835. A few hundred yards away is Fish Street Hill - now a nondescript road filled with banks and caught between the pounding traffic of two major roads - where the medieval fishmongers sold their wares. It was up this lane that Henry V and his soldiers first paraded when they returned in triumph from Agincourt. When you stand in the rain, watching taxis jammed together and City workers hustling along, it is tempting to imagine the whole street decoated with flags and banners, and the clank of armour and horses as the king and his men filed up the hill.

In an attempt to thread together some of the sites into a narrative, the String of Pearls festival has published guides which allow you to follow a particular theme. For instance, The Trail of Thomas More allows you to follow in the footsteps of Henry VIII’s chancellor (from 1529 to 1532), whose rise and fall has come to epitomise the struggle between personal conscience and political expediency. You can begin at Thomas More’s birthplace, in Milk Street in the City, and follow where he went to school, studied as a lawyer, where he lived (27 acres in Chelsea, bought for pound;30), through to his trial for treason in Westminster Hall and to his execution at Tower Hill. The cell in the Tower of London where it is thought he was kept before his beheading has been opened for the first time for the festival.

Whether you follow a trail with a particular theme or whether you just ramble along between a few of the riverside venues, the best way to see the pearls of Thamesside London is by walking. Even though the capital might seem to be filled to the point of exhaustion and overwhelmed with tourists, the riverside can still give you a sense of open space and glimpses of a quieter and older London. This is particularly so if you visit the String of Pearl venues on the south bank of the Thames, around Bankside, Bermondsey and by following the Thames path along the Rotherhithe waterfront to Deptford and Greenwich - you can feel as though you’ve left behind the scrum of metropolitan living.

As well as giving access to significant buildings, the String of Pearls festival organisers want to use sites as venues for music, drama and dance. The Shipwright’s Palace is to host a new play about the life of the playwright Christopher Marlowe, who was killed in a tavern on Deptford High Street and buried in an unmarked grave in the nearby St Nicholas’s Church (where there is a commemorative plaque).

This festival is a reminder to visitors and Londoners alike of the weight of history in the capital. People have been living and working on the Thames riverbanks since pre-Roman times and the String of Pearls shows how layer upon layer of life is lying beneath our feet. In fact, the project is a spur to the imagination and a way of encouraging people to think more closely about how cities develop.

* The London String of Pearls Millennium Festival, tel: 020 7665 1540.

www.stringofpearls.org.uk.

The festival will run for the whole of 2000 with exhibitions, events and other happenings taking place at different times. The website events listings are updated as details are confirmed.

Lambeth Palace, London SE1 7JU. Open April-November, Tuesdays-Saturdays. Pre-booked tours only, write to the secretary. Theme: faith.

Shipwright’s Palace, Deptford. Open April-October, hours and costs vary with each event. Theme: Defence of the Realm.

Houses of Parliament, Westminster Palace.

Exhibition open August and September, 9.30am-5pm.

Theme: democracy.

Fishmongers’ Hall, City of London. Open two Mondays each month for guided tours except July to September inclusive. Theme: trade, commerce and enterprise.

BBC World Service, Bush House. Exhibition open June and July. Theme: freedom of speech and the media.

London School of Economics, tel: 020 7955 6043. Most events free. Theme: knowledge, learning and education.

HM Tower of London, London EC3N 4AB. Tel: 020 7488 56623. Visitors can see Sir Thomas More’s cell.