The historical core of the city is on the east bank of the Sufi Chay, which comes down from Mount Sahand before turning west and eventually flows out into Lake Urmia. The climate is relatively mild and moist, and the abundant water supply makes the surrounding area very fertile. Maragheh is surrounded by extensive vineyards and orchards, all well watered by canals led from the river, and producing great quantities of fruit. The hills west of the town consist of horizontal strata of sandstone covered with irregular pieces of basalt. The remains of the historic Maragheh observatory crown one of these hills. Maragheh lies just off the main highway from Tabriz to Kermanshah, which instead goes through Bonab further west. Another important road skirts around the south and southeast sides of Mount Sahand and connects Maragheh with Ardabil and Zanjan further east. Maragha observatory On a hill west of the town are the remains of the famous Maragheh observatory called Rasad Khaneh, constructed under the direction the Ilkhanid king, Hülagü Khan for Nasir al-Din al-Tusi. The building, which no doubt served as a citadel as well, enclosed a space of 340 by 135 meters, and the foundations of the walls were 1.3 to 2 meters in thickness. The observatory was constructed in the thirteenth century and was said to house a staff of at least ten astronomers and a librarian who was in charge of the library which allegedly contained over 40,000 books. This observatory was one of the most prestigious during the medieval times in the Islamic Empire during the golden age of Islamic science. The famous astronomer Ibn al-Shatir of Damascus built on the work of Maragha astronomers 100 years later. In 1256 Nasir al-Din al-Tusi came to work at the Maragheh observatory after being attacked by a group of Mongols who came from the east. These Mongols ambushed Iran, crushing everything in their path. Nasir al-Din al-Tusi was located at the Alamut, a castle in the South Caspian province of Qazin, when the Mongols invaded. Hulagu Khan was the leader of the Mongols and grandson of Genghis Khan. He was a fearless leader and warrior who was determined to conquer not only the Alamut, but many other countries across the globe as well. In order to spare his life, Nasir al-Din al-Tusi told Hulagu that he could predict the future if only he had better equipment. Being