India’s first passenger train journey took place on 16 April, 1853, between Bombay and Thane. In 1951 Indian Railway systems were nationalised as one unit – Indian Railways – to form one of the largest networks in the world. The only steam engines still in service in India operate on two heritage lines (Darjeeling and Ooty), and on the tourist train Palace on Wheels. The oldest steam engine in the world in regular service, the Fairy Queen, operates between Delhi and Alwar. The Chittaranjan Locomotive Works makes electric locomotives. The Diesel Locomotive Works in Varanasi makes diesel locomotives. The Integral Coach Factory in Perambur makes integral coaches. The Rail Coach Factory in Kapurthala also makes coaches. The Rail Wheel Factory at Yelahanka manufactures wheels and axles. In 2003, the Indian Railways celebrated 150 years of its existence. Various zones of the railways celebrated the event by running heritage trains on routes similar to the ones on which the first trains in the zones ran. The Ministry of Railways commemorated the event by launching a special logo celebrating the completion of 150 years of service. Also launched was a new mascot for the 150th year celebrations, named “Bholu the guard elephant”.