Kalyan is located by the estuary of the Ulhas river with access to the Arabian sea
. Located around 50 km to the northeast of Mumbai
, Kalyan was a port during the Gupta period. The ruins strewn about the city are proof of its earlier glory. Kalyan was earlier occupied by the Bijapur sultanate (a Muslim state) in the 1500s, and later by the Mughal emperor Shah Jahan
, who fortified the city in the mid 1600s. Later the Marathas occupied the area, when Kalyan became one of the strategic centers on account of its position at the entrance to Bombay and the western coast of India. After the British defeated the Marathas at the end of the 18th century, Kalyan became part of the Bombay Presidency, a British region that became Bombay state after India's independence in 1947.
Now there is an important railway station at Kalyan for suburban travel as well as for long distance trains. Kalyan is directly connected by rail to Mumbai. Rice mills, textile-based cottage industries, and factories making car spare parts are located in this region. On the eastern side of the city there is a large industrial complex where electrical equipment, rayons, dyes, and other chemicals are manufactured. Nearby is the Hajimalang Darga on Malangagad hill.
The nearest airport is Chhatrapati Shivaji International airport.