The Ulugh Beg Observatory in Samarkand, Uzbekistan, is a significant historical astronomical observatory, built by the Timurid astronomer Ulugh Beg in 1420. It is part of the Samarkand - Crossroads of Cultures UNESCO World Heritage site, underscoring its importance in scientific history. Ulugh Beg, the grandson of Timur (Tamerlane), was not only a ruler but also a renowned mathematician and astronomer. The observatory was once a major center for study, attracting scholars from all over the Islamic world. The most notable instrument within the observatory was a huge sextant with a radius of 40.2 meters, used for measuring the position of stars and computing celestial coordinates with unprecedented precision. The observatory's main purpose was to reform the astronomical tables and improve the accuracy of celestial predictions. It contributed to the Zij-i-Sultani, a star catalog and almanac, which had an enormous influence on the development of astronomy. Although the site was destroyed in the late 1440s, excavations in the 20th century have partially revealed the original foundation, bringing some of Ulugh Beg's incredible scientific work back into the limelight.