Sienese altarpiece parts reunited after 400 years

For centuries the separate panels of the altarpiece of the Church of St Agostino in Asciano lay in different corners of the world, unrecognised by art dealers and critics alike as being parts of one magnificent work. Now, the reconstructed altarpiece is to be the highlight of a new exhibition at the National Gallery.

Depicting in glorious Renaissance colour the biblical scene of the Assumption, parts of the wooden polyptych painted by the 15th century artist Matteo di Giovanni had until today been displayed separately in Italy, America and the UK. Originally commissioned for the local church of Asciano, a little town just outside Siena in Tuscany, the towering Assumption of the Virgin altarpiece dates from 1474 but was taken apart in the 17th century when the popularity of Sienese art was on the wane and Florence was becoming the new capital of the Renaissance.

That the altarpiece had once been a unified work was forgotten until experts, fed up with centuries of speculation over its heritage, attempted to find definitive proof that the panels had indeed been envisaged as a whole.

Earlier this year, Luke Syson, from the National Gallery, which has owned the central panel piece since 1884, removed the main panel from its 19th century frame to discover peg holes that exactly matched those in the smaller panels in Italy.

While Mr Syson's discovery came at the end of four years of dogged research, he said yesterday that putting the piece together for the first time in more than 300 years would be a "moving moment" for him.

"To recapture the original impact of this altarpiece which was immense when it was originally displayed... is a grand and uplifting experience and seeing them together is terribly moving," he said.

The altarpiece as a whole is made up of five separate panels. Mr Syson discovered the two main side pieces in a small museum in Asciano, depicting St Augustine and St Michael. The biggest panel could not be moved from London because it was so large. A fourth panel was acquired by a gallery in the United States and the fifth was bought by a private collector.

The altarpiece was initially envisaged by Di Giovanni when he was working in Asciano. After the Sienese art boom passed its prime, however, it was dismantled and placed in a dry wood store until its rediscovery in 1800 when a wealthy family in Siena bought it for their private chapel. Although experts knew the panels were supposed to be displayed together, no one, at the time, cared about keeping them in one place, said Mr Syson.

So the central panel came to London while the other sections of the altarpiece surfaced on the market in the 19th century.

The reconstructed piece is one of the greatest highlights of the gallery's exhibition, Renaissance Siena: Art for a City, opening on 24 October. The show attempts to rediscover the worth of Siena's principal artists, including Di Giovanni, Francesco di Giorgio and Domenico Beccafumi who all fell out of fashion in the 17th century. Their names are barely known outside Siena and the city's main art gallery, the Pinacoteca Nazionale, struggles to attract tourists, while their Florentine counterparts such as Giotto di Bondone and Michelangelo have become known as Italy's art superstars and their work lures millions of tourists every year.