Qom is one of the holiest cities in Iran and the middle East. The famous thing about Qom is the Hazrat-e-Massummeh Shrine which is a highly respected shrine. The city can be visited in an easy day trip from Tehran or en route to Kashan.
Qom is the main city for religious studies in Iran for long. Hozeye-Elmiye-Qom is the largest Theology school in Iran. Right now many Senior ranking clerics of Shia Islam live in Qom.