Short answers, pulled from the story.
The Ulugh Beg Observatory is a medieval astronomical facility located in the heart of Samarkand, Uzbekistan. It features the largest astronomical instrument ever constructed in the medieval world, which is a massive sextant carved directly into the ground with a radius of 40.04 meters.
Ulugh Beg, the grandson of the great conqueror Timur, built the observatory in the 1420s. He transformed Samarkand into a beacon of scientific inquiry by inviting over sixty mathematicians and astronomers to populate the facility.
The Zij-i Sultani is a star catalog published in 1437 that listed approximately one thousand stars with unprecedented precision. It included a sine table spanning eighteen pages and determined the length of the tropical year as 365 days, 5 hours, 49 minutes, and 15 seconds.
The observatory fell into ruin after Ulugh Beg was assassinated by his own son, Abd al Latif, in 1449. This political violence caused immediate chaos that drove away dozens of talented astronomers and mathematicians, leaving the institution without protection or funding.
Architects designed the observatory as a partially subterranean structure to maintain structural integrity because the soft bricks of the region could not support a tall tower. They dug a trench roughly two meters wide to house the lower section of the meridian arc, allowing the sextant to reach its full scale without collapsing.
Jamshid al-Kashi served as the first director of the observatory, followed by Qadi Zada Rumi and finally Ali Qushji. These scholars worked together to measure the positions of thousands of stars and integrated astrology into their daily work alongside celestial mechanics.