The fountains don't work. The flower beds are off-limits. The staff are stroppy. Welcome to Italy's top garden

The garden at Villa Lante, which crowns the small hill town of Bagnaia in the Lazio region of Italy, is said by connoisseurs to be the least changed and best preserved of any of the great gardens of the Italian Renaissance. Last week, on my first trip to Italy, I approached it in the spirit of a pilgrim. For any one who loves gardens, this place seemed to be a touchstone, the beginning (almost) of the story of the pleasure garden in Europe, the font of many of the ideas that still have an abiding influence on the way we plan our patches.

Bagnaia, with houses that grow seamlessly out of the sheer rock faces rising from the valley, is one of those small places that minds its own business, has plenty of business to mind, and therefore provides endless delight for day-trippers. You can sit for hours in the square over coffee or grappa, drawn willy-nilly into the soap opera going on around you. In no other country does it seem to matter less that you cannot speak the language. Here, body language says as much as words.

From the square, the narrow Via Giambologna leads directly to the gate that was designed as the main entrance to the garden. This is the end of the long, dramatic vista that stretches up and back over fountains and pools, terraces and stairways to the grotto at the far end of the garden, where the water that provides the central backbone of the design starts its long journey.

This is the entrance that Cardinal Gambara, who began constructing the garden in 1568, would have used. Visitors were brought in through another entrance on the right, past the fountain of Pegasus shown in an early 17th-century plan of the garden. The Lex Hortorum (law of the garden) of the period guaranteed access for all - free.

This same side entrance, still in use today, brings you out on a broadwalk between the great parterre at the end of the garden, on the left, and a bank, sternly bisected by box hedges, that rises between the two square villas that make a matched pair either side of the central vista.

The big parterre on the left, with its dramatic centrepiece of fountain and stone boats, was roped off when I visited. Since the garden was almost empty, I tried hopping over the rope to get to the fountain, but a roar and a great deal of body language from the ticket collector put paid to this little bid for freedom. The parterre was off the menu. As it turned out, so was much else.

The garden climbs the hill by way of a series of dramatic set-pieces: the Fountain of the Lights; the Water Table; the Fountain of the River Gods; the Water Chain; the Fountain of the Dolphins; and, finally, the Grotto. The whole sequence tells the story of man's journey from the wilderness (the grotto) to the state of high civilisation that married nature and art in the intricacies of the final parterre.

Having marked me down as a trouble-maker, the ticket man shooed me up the stairs at a brisk trot which meant that it was only at the Fountain of the Lights, on the next terrace, that I could turn again to look at the bottom parterre.

The initial view from Gambara's entrance gate had shown that it was thick with weeds. That didn't matter. But there were puzzling ragged holes in the middle of the big clipped squares of yew that punctuated the 12 box- edged beds.

Mark Laird's fine book The Formal Garden solved that problem. Every photograph of that famous parterre shows big terracotta pots containing orange trees filling these holes and flanking the steps between the terraces. But there was not a single pot in the entire garden.

And the fountain was not playing. Now that all the flowers Gambara planted in the parterre have gone, along with the fruit trees that once surrounded it, you need moving water to bring life to the severe, static layout. But the water surrounding the stone boats was as still as glass. Not a drop came from the boatmen who once blew jets from their stone muskets. (I think they were muskets - it was difficult to tell at the distance I had been put by the ticket collector.)

"Up, up" was the unmistakable message from the ticket collector's arm. He was still hovering, perhaps to see whether I was going to jump the barricades that shut off the grottoes to Neptune and Venus. The rose garden on the left-hand side was also out of bounds. So were the loggias of the muses.

Up, up was the only option, especially as the Fountain of the Lights at this level had evidently jammed. The concentric semi-circles of stone, lined with miniature jets, were scarcely dribbling. A broom handle thrust into a pipe between one level of the fountain and the next suggested that somebody, somewhere, might be doing something about the problem. But not today.

An immense stone table lies between the Fountain of the Lights and the Fountain of the River Gods, with a deep water-filled channel about a foot wide carved down its centre. This makes a serene link between the grotesque masks at either end, which spew water into a shallow, narrow moat around the base of the table. It's always described as a table; but in fact, when you look along it, you see that the top is laid not flat but in a smooth, gentle convex curve: very beautiful, but expensive on plates.

Behind the massive, benign figures of the sea-gods, stairs lead up either side to meet on the next level. A descending series of pillars, each topped by an empty urn, makes a stone banister up the edge of the steps. Spouts in the top of the urns show that they too were once miniature fountains.

But there was a wonderful surprise on the stairway. As I turned to go up it, I found that the entire balustrade, which seemed to be just stone, was in fact a water chute. The water passed under each urn in turn and rolled down a scroll of stone into an oval basin hollowed out at each step. At the top was another balustrade, which I had seen in a picture spewing water patterns as intricate as lace, but was now dry and lifeless.

It was at this stage that I stopped making excuses for the Villa Lante. At first I had thought there might be a water shortage, having just arrived from drought- struck England. But then I remembered that my Italian neighbours had told me this had been a staggeringly wet summer for them.

Then I wondered if there was a problem with gardeners, but there were three men sweeping gravel on one of the paths. Why was so much of the garden roped off? Why were so many of the waterworks not working? Why were the box hedges quite so full of holes? Why, in a garden full of fabulous stonework, were the paths covered in gravel of such a deadly colour?

In the meantime, I had worked my way to the grotto at the top of the garden and back down again, past the brilliant Water Chain. This is made by a series of stone scrolls, almost meeting and dividing in a sinuous double string down the hillside, the water rushing down through the middle.

I had been in the garden just three hours and, since there was still an hour and a half till closing time, I thought I would do the circuit a second time. Something might have happened with the broomstick. The rose garden might suddenly be open.

But the man on the gate had other ideas. Advancing sternly down the broadwalk, he started tapping his watch fiercely and pointing to the door. In what I hoped was a meaningful way, I pointed in turn to the board that quite clearly stated that the garden was open until half past five. But it was an unequal contest. As the door was locked behind me, I heard the soft, musical sound of water. The fountain was beginning to play in the parterre.

The Villa Lante is open daily from 9am to 5.30pm (in theory). Admission 4,000 lire.