The Neishapur train disaster was a large explosion in the village of Khayyam near Nishapur in Iran, on 18 February 2004. Nearly 300 people were killed and the entire village destroyed when runaway train wagons crashed into the community in the middle of the night and exploded, resulting in Iran's deadliest rail disaster to ever occur. It is still unexplained how the parked train had come loose and was able to travel such a long distance with no driver or guard.

Nishapur or officially Romanized as Neyshabur (Persian: نیشابور; also Romanized as Nišâpur, Nişapur or Nīshābūr; from Middle Persian New-Shabuhr, meaning "New City of Shapur", "Fair Shapur", or "Perfect built of Shapur") is the second largest city of Razavi Khorasan Province, the historic capital of the western half of Greater Khorasan, the historic capital of the 9th century Tahirid dynasty, the initial capital of the 11th century Seljuk Empire, the capital city of Nishapur County and a historic Silk Road city in Northeastern Iran.

Nishapur is situated in a fertile plain at the foot of Binalud Mountain Range. As of 2016, its central city population was estimated to be 264,180 and its county's population was estimated to be 448,125 making it the third most-populous city in the eastern provinces of Iran. Nearby are turquoise mines that have supplied the world with turquoise of the highest quality for at least two millenniums. The modern city of Nishapur comprises three administrative districts.

The city was founded in the 3rd century by Shapur I as a capital city of Sasanian satrapy known as Abarshahr or Nishapur. Nishapur later became the capital of Tahirid dynasty and was reformed by Abdullah Tahir in 830, and was later selected as the capital of Seljuk dynasty by Tughril in 1037. From the Abbasid era to the Mongol invasion of Khwarezmia and Eastern Iran, the city evolved into a significant cultural, commercial, and intellectual center within the Islamic world. Nishapur, along with Merv, Herat and Balkh, were one of the four great cities of Greater Khorasan and one of the greatest cities of the Old World in the middle ages, a seat of governmental power in the eastern section of caliphate, a dwelling place for diverse ethnic and religious groups, a trading stop on commercial routes from Transoxiana, China, Iraq and Egypt.

Nishapur reached the height of its prosperity under the Samanids in the 10th century but was destroyed and its entire population was slaughtered by the Mongols in 1221. This massacre, combined with subsequent earthquakes and other invasions, is believed to have destroyed the city several times. Unlike its near neighbor Merv, Nishapur managed to recover from these cataclysmic events, and survive until the present day.

Many of this city's archeological discoveries are held and shown to the public in the Metropolitan Museum of Art in New York City, the British Museum in London, and other international museums. Nishapur is also a member of the League of Historical Cities (LHC).