OXFORD'S shopping precinct in the Cornmarket, and the squalor and detritus it has created in the centre of one of the loveliest cities in the world, is an act of vandalism equivalent to putting false eyelashes on a Rembrandt or saucy underwear on a Rodin.

How the city fathers, let alone the proud and pursy university authorities, allowed it to happen beggars comprehension. But do not despair: the visitor to Oxford can avoid the squalor and find a serene and private city.

Many colleges nowadays are closed to outsiders, either at certain times or altogether: but college porters (those all-seeing figures who sit in wooden lodges just inside the gnarled double doors that open on to the inner college quadrangles) are kindly fellows. If they tell you the grounds are closed to visitors, a charmingly wistful smile and a murmur of, 'Oh, and my cousin/brother/great-grandfather was here . . . ' will often change their minds. And if not, who can blame them?

I heard one party interested only to know, 'Did Morse ever come here?' If Inspector Morse has become Oxford's most famous character - and he has - it is hard to see why colleges should make themselves available to every passing TV-freak in search of small-screen heroes.

Once inside the college doorway, head for the garden (if fine) and the chapel (if wet).

Every college has one of each; both are nearly always magnificent. The gardens in high summer are a glory of herbaceous borders, age-old trees, and lawns of incomparable green, the pile lying in two perfectly opposed stripes. (The story of the American visitor who asked the gardener how these lawns reached such perfection bears repeating. 'It's quite simple. You just mow them and roll them, mow them and roll them.' 'But I do that already]' 'Just keep on doing it for 400 years.')

Visiting Trinity College, we walked through the tall, elaborate wrought-iron gates that lead to the cool expanse of garden. Here we strolled in perfect solitude, admiring the riot of contrasting colour and texture of a 100-metre border, as well as its environmentally correct area of rough garden, allowed to run wild. From the far side of the old stone wall, the murmur of passing traffic was barely audible.

The college's 17th-century chapel is a revelation. As you push open the heavy door, your nostrils are assailed by the rich, sweet smell of old wood. Inside, the chapel boasts a cornucopia of carvings in limewood by Grinling Gibbons - swags and ribbons and cherubs' heads, fruit and vegetables and buds and foliage, looping and coiling in glorious profusion.

It is panelled with ancient juniper, polished now to a high, fox-coloured patina. The painted ceiling is equally exuberant. Other than an American bringing his awed children to see where Pa had once studied, we were the only visitors.

From Trinity in the Broad it is a 10-minute walk up St Giles to Banbury Road. Pass the Martyrs' Memorial - 'Be of good cheer, Master Ridley,' remarked Latimer as the flames rose, 'for we shall on this day light such a candle as shall by God's grace never be put out' - and just a couple of hundred metres north is The Old Parsonage, where you can park, and have a drink or a meal in the peace of a high-walled garden.

Indoors, if you prefer, tables and armchairs and sofas are informally arranged beneath an eclectic array of pictures. The waiters are French and efficient; the wines well-priced. Three of us lunched for just over pounds 30, in comfort and without hearing a raised or intrusive voice.

After lunch we walked along Catte Street, past Hertford College's copy of the Bridge of Sighs, towards Radcliffe Square, so as to enjoy the mathematically satisfying juxtaposition of a cube (the corner of the Bodleian), a dome (of the Radcliffe Camera) and a triangle (spire of the university church of St Mary's). As you pass Hertford, stand with All Souls ahead on your left, looking diagonally towards Brasenose, and move slowly towards the Radcliffe Camera. The shapes move gradually together until they lock in perfect conjunction.

Walk briefly down the High towards Magdalen, turning right along Merton Street until you reach that dear medieval college, the first to be established in Oxford or Cambridge. (Cantabrians will dispute this, of course, but they are in error.)

Merton is open to visitors nearly every afternoon. Mob Quad, built in the 14th century, gives a good impression of the crowded, clerical atmosphere of the university at the beginning of its rise to one of Europe's centres of learning. Beyond Mob Quad lies Merton's 13th-century chapel. Do not miss the monument to Sir Thomas Bodley, whose alabaster-and-marble effigy is flanked with books (he founded the Bodleian Library), or the huge bowl of Siberian green marble, polished, opulent, empty and useless, given by Czar Alexander in 1816 (heaven knows why).

If you can find the way in, Merton's garden is, to my mind (but judgement may be blurred by nostalgia) the most beautiful in the city.

Oxford, like art galleries, is much better savoured in a few slow and concentrated sections than swallowed whole. Gallop round the National Gallery in two hours and you will remember nothing. Attempt to visit 10, or 12, let alone more colleges in a day or even a weekend, and they will slide into a formless blur of ochre stone. You are likely to come away finding that the detritus is your clearest recollection.

But if you look at two, at most three, colleges in a day, at leisure, allowing your imagination to work and the atmosphere to steal over you, alert for the small details, then Oxford will be seen for what it still, just, is: a city so glorious, so rich, that I once watched with gratified pride as a resident of

St Petersburg (no stranger to architectural wonders) was struck dumb by its beauty.

If you stay overnight, do so at a hotel outside the city.

Weston Manor, at Weston-

on-the-Green, eight miles north of the centre of Oxford, is a 14th-century manor house with a panelled dining room and minstrels' gallery and

13-acre garden. It offers

bargain weekend breaks in August, at pounds 99 per person for two nights: telephone 0869 350621.

q The Old Parsonage, 1 Ban

bury Road, Oxford. Tel: 0865 310210.

For further information you can try the Visitor Information Centre on 0865 726871. Try may be the operative word - priority being given to those who arrive in the office.

(Photograph omitted)