Ulug Beg Observatory

Medieval Samarkand was a centre for both religious and secular learning, and his rulers patronised the sciences as well as the arts. Ulug Beg's Observatory (Tashkent; 09.00-18.00 daily; foreigners US$2), one of the largest astronomical observatories of the period, lies a brisk, ten minute walk past Afrosiab and into the foothills. 15th century observatory is the crowning achievement and path to disaster of Tamerlane's grandson, astronomer-king Ulug Beg.T he observatory lay forgotten and in ruins for some 500 years prior to its partial restoration, the important work undertaken there remembered only in Ulug Beg's astronomical works, which had been published posthumously in Europe.

In 1908, the mystery of its whereabouts was solved after years of painstaking research by Russian archaeologist Vladimir Viyatkin. Today visitors can view his discovery, the underground section of a vast meridian arc, ignored by the fanatics who destroyed the building in 1449. Quadrant arc 63m in length was used to chart the progress of celestial bodies across the sky. Using this arc, Samarkand's medieval astronomers produced a star catalogue charting the movements of 1,018 stars, which was still known and studied in Oxford in the 17th century.

It was the largest 90° quadrant the world had ever seen, though it is called a sextant as only 60° were used. Deeply embedded in the rock to lessen seismic disturbance, the surviving 11-metre arc sweeps upwards in two marble parapets cut with minute and degree calibrations for the astrolabe that ran its length. The arc completed its radius at the top of a three-storey building.

When you first arrive at the site you'd be forgiven for thinking that there's nothing to see: only a modern portal is visible. The arc itself is sunk below ground, which is the reason it survived when the rest of the observatory was destroyed by fanatics in 1449.  Descend into the gloom, and you will be struck by the scale of the arc but also the precision with which it was made: tiny niches are cut into the surface for calibrating the once-accompanying astrolabe, enabling exact calculations to be made. In fact, their accuracy would not be beaten until the invention of the computer.

Above ground floor service rooms were arcades designed as astronomical instruments. A witness described the planetarium-like decoration: 'Inside the rooms he had painted and written the image of the nine celestial orbits and the shapes of the nine heavenly bodies, and the degrees, minutes and seconds of the epicycles; the seven planets and pictures of the fixed stars, the image of the terrestrial globe, pictures of the climes with mountains, seas and deserts.

The sextant is now covered by a portal and vault at the centre of the observatory's foundations. Viyatkin's grave lies nearby, as he had requested. A memorial museum (open 9am-7pm daily) details the careers of Tamerlane and his grandson. Ulug Beg's scientific success, the culmination of a Central Asian tradition including al-Khorezmi, al-Beruni and Avicenna, is set alongside the political failures that cost him his life. The observatory lies a further ten minutes' walk northeast from Afrosiab Museum-the same marshrutka apply.

Alongside the arc and its portal is the grave of Viyatkin and a small museum (09.00-18.00 daily) about Ulug Beg's life and works.