TAPESTRY WEAVING.

A little archaeological museum connects millennia and urban patterns ancient and modern with grace and invention.

Naxos is the largest island of the Cyclades archipelago in the Aegean Sea, south-east of Athens, about halfway between Greece and Turkey. From earliest times, the island's fertility (and wine making) have been celebrated, and it bears traces of constant civilization from the times of the Mycenaeans (1300BC and earlier) through Classical and Hellenistic times and the successive empires of the Romans, Byzantines, Venetians and Ottomans, all of which left traces above and below ground. On top of them all is the small town with winding lanes lined with immemorial white Cycladean houses, little churches, wonderful exercises in solid geometry, and, on the edge of the old settlement, an Orthodox cathedral with four bells hung high up in a curly crowned west front.

Couvelas' basic design emerges from the contrast between a modern grid, roughly orientated to the east like the churches, and the ancient axes, which are set at about 45 degrees to the contemporary ones. The lower level naturally takes the ancient orientation, and much of the immediately obvious impact of the new project comes from the contrast between the two generating directions. They are resolved calmly and without fuss (how very different from the clashing grids so fashionable in the late '80s). A ramp and an arc of stone amphitheatric stairs take you from street level to the first lower plane of ground, and from there again similar devices lead gently down to the entrance court.

An important archaeological sire has been excavated next to the forecourt of the cathedral, and Agnes Couvelas was given the job of making a museum that would protect the remains and allow them to be seen in situ. The earliest and lowest levels include par t of the Mycenaean city wall and remains of pottery and bronze workshops (1300-1100BC). Above is a cemetery which was in use between 1100 and 700BC. Above that are fragments of all the successive dominant cultures of the island.

The museum in its hollow at first seems to be a precise, almost Miesian metal and glass pavilion. But the entrance is further in, under a steel bridge, and the inner court makes plain that we are about to enter mysteries of the earth. Inside, there is basically one route round the place, with a couple of cul-de-sac extensions. A timber deck is suspended from the concrete slab roof. It winds round the perimeter of the space, letting you see the Mycenaean wall, the remains of the cemetery and, sometimes where timber is replaced by glass, revealing deeper and even more ancient layers. A sombre brick wall surrounds the space, allowing the floodlit ruins to speak for themselves: the steel, glass and wood deck floats over them, without interfering with their integrity and power.

Outside again, under the heat and intense light, the shade and coolness of the modern cave of mysteries becomes a memory. You can see it echoed in the handling of materials and surfaces in the new square that has been created to connect the cathedral and the four surrounding little churches. The museum itself is marked by a square of rough local marble slabs to keep the cave cool and free of humidity. Important moments, like the curved stairs, are in a smoother version of the same stone. Continuo is maintained with smooth rounded cobbles from the seashore, used just as they were thousands of years ago. Round the edge of the lower area is a gently curving wall of dark red bricks, similar to those used inside the museum, and used for the same purpose, to achieve a modern, anonymous machine-made backdrop against which craftsmanship can speak. The masterstroke is the light and elegant bridge over the museum forecourt. Like the deck in the gallery, it is made of very precisely and austerely detailed steel and tim ber. It is, says Couvelas, 'a thread darning the hole caused by the excavation', and, in the darning, the pattern of the old weave of the city has been brought to the surface to take part in the modern tapestry.