A good way to get the feel of monastic life in medieval England is to spend some time in the cloisters of Gloucester Cathedral, a perfectly-preserved square of walkways with elaborate fan-vaulted ceilings and gothic windows which filter the light on to the cold flagstones.
It's one of the cathedral's most famous features, along with the alabaster tomb of Edward II and the east window, a great wall of blue and ruby glass the size of a tennis court. As you walk slowly round the cloisters, it's easy to sense an echo of shuffling footsteps on a 14th-century winter afternoon.
There's a long, low lavatorium alongside the north cloister, where the monks washed, and little carrels or alcoves in the walls where they studied. The younger ones sat and played fox and geese or nine men's morris - the markings for the games are scratched into the stone seats.
"It's my favourite part of the building," says the cathedral's education officer, Christine Crago. "If you're in there on your own, the feeling that the Benedictine monks are there with you is quite strong, particularly in the late evening or at night. You can imagine them in their black habits, having a meeting in the chapter house or walking around in silence."
Among the latest visitors to the cloisters are Warner Brothers, who used them as part of Hogwart's School for the film of Harry Potter and the Sorcerer's Stone, due out later this year: pupils at the choir school were recruited as extras, and the city council's tourist department is now busy marketing Harry Potter chocolate frogs and gobstoppers.
The preservation of the cloisters was partly due to Henry VIII, who let Gloucester Abbey off lightly at the dissolution of the monasteries in 1536 because one of his ancestors, Edward II, was buried there. A few years later, Henry made the Abbey's church the cathedral of the new Church of England diocese of Gloucester.
The murder of Edward, widely regarded as a weak ruler, was also the cause of the construction of the cathedral's most dramatic architectural feature - the choir and presbytery, built in soaring perpendicular style between the massive columns of the original Norman building like a delicate jewel casket slotted carefully into place.
Despite his weaknesses and entourage of favourites, Edward was popular with ordinary people, and the money from pilgrims visiting his tomb made the new building possible. "I compare him to Diana Princess of Wales when I'm showing school parties round," says Mrs Crago.
The reputed manner of Edward's death also presents her with her most delicate educational challenge. If the teacher agrees, she tells them as politely as possible that he had a hot poker stuck up his bottom: "They clench their buttocks and go 'ooh' and roll their eyes.
"But the fact is that children are drawn to the gory stories: they also like the Prentice Bracket, a stone carving commemorating the death of a young stonemason who fell to his death during the construction of the cathedral tower. I try to get across that it's not just a building but a collection of people and stories."
The preservation of the 11-acre enclave of ecclesiastical buildings around the cathedral means that Gloucester is often used by film and TV companies in need of period settings. And while some cathedrals are great craggy monsters, Gloucester is a little gem, with an exuberantly decorated tower topped by four tall and delicate turrets.
The east window, huge and delicately-coloured, was built as a memorial to the battle of Crécy and is currently being stripped of some ill-advised supporting ironwork put in by the Victorians. In one corner is a panel showing a man playing bandy ball, which looks like an early form of golf: very popular with American visitors.
The rest of the city, which Beatrix Potter celebrated in her illustrations to The Tailor of Gloucester, suffered badly in the municipal vandalism of the 1960s, when concrete was king. Parts of its Roman, Saxon and medieval heritage, potentially as rich as that of Chester or York, were obscured, damaged or neglected and are only now being rehabilitated.
A good example is Blackfriars, the medieval Dominican monastery in the city centre, which has an impressive scissor-braced roof in its main building, and a library and refectory, which until recently was used as a mineral-water bottling factory. At present, you can only visit by arrangement, but there are plans to increase access.
Gloucester was always a robust working town, and since its large inland port on the River Severn and Sharpness Canal fell into disuse, the great corn warehouses at the old docks have been converted. One of them is the National Waterways Museum, where you can navigate a boat through a lock. Another is the Museum of Advertising and Packaging - Robert Opie's huge collection of tins, bottles, signs and boxes dating from 1870. The Soldiers of Gloucester Museum is also there, telling the story of local men defeating Napoleon or retreating from Dunkirk; another warehouse is now a huge antiques centre.
Philip Moss is a local historian and illustrator who guides visitors to interesting sights tucked away down sidestreets, such as a three-story half-timbered medieval house wall with original glass and window catches. It's so close to its modern neighbour you have to sidle down an alleyway called Maverdine Lane and crane up at it.
In College Court, The House of the Tailor of Gloucester is a small museum with a faithful recreation of the tailor's kitchen and a replica of the famous coat. And the New Inn in Northgate Street is the best-preserved galleried courtyard inn in England, now a modern pub and hotel.
Gloucester may not be as immediately attractive as Cheltenham, its Georgian neighbour, but Moss says its people are forthright, friendly and welcoming. "Reputation means nothing and they take people as they come," he says. "They're very proud of their history, and a bit more is being done now to bring it out."
What to see on a stroll round Gloucester
1 Bishop Hooper's Monument, erected in 1862 near the cathedral to John Hooper, who took three-quarters of an hour to die when Bloody Mary burnt him at the stake in 1555.
2 The Parliament House in the cathedral precincts, where Parliament sat in 1378: Richard II had just introduced the unpopular poll tax and was too scared to hold it in London.
3 The Chapter House off the cloisters, where William the Conqueror gave the order for the Domesday Book to be compiled.
4 A Victorian window in the cathedral's south aisle showing Henry III being crowned at the age of seven with his mother's bracelet.
5 The painted wooden effigy in the south ambulatory of Robert, Duke of Normandy, son of William the Conqueror. His legs are crossed to mark a Crusader.
6 The glowing blue of the modern stained glass by Thomas Denny in the south ambulatory chapel: the theme is Psalm 148, Praise him sun and moon...
7 The bollards in Southgate Street shaped like pins - a reference to one of Gloucester's industries.
8 The Raikes House in Southgate Street, home of Robert Raikes the younger, founder of the Sunday School movement in the 18th century.
9 The Gloucester Folk Museum: junior visitors can take part in a strictly-run Victorian classroom.
10 The parish church of St Nicholas in Westgate Street: its spire was knocked off in the Civil War, and what's left has a dramatic tilt.
Way to go
Gloucester is on junctions 11 and 12 of the M5 and is 1 hours from London by train: national rail enquiries: 08457 484950. For coach services, ring National Express (08705 808080). For transport and accommodation information and a copy of the visitors' guide, call Gloucester Tourist Information Centre, 01452 396572, www.gloucester.gov.uk . For information about the docks, 01452 311190, www.glosdocks.co.uk. For information about the cathedral, including sung services, 01452 528095, www.gloucestercathedral.uk.com. Events this summer include the Three Choirs Festival in August (01452 529819), arts events in Gloucester Festival, July 14-28 (01452 396666) and re-enactments of the siege of the city in the Civil War on August 18-19 and 25-27 (01452 396571).
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