Mumbai GPO is biggest post office in the country.

The General Post Office is modelled on the Gol Gumbaz in Bijapur, Karnataka. It was designed by British architect John Begg, a consultant architect to the British government. Begg designed the structure in 1902, and construction began on 1 September 1904. It was completed on 13th March 1913 at a cost of Rs. 1,809,000. Black basalt, with a dressing of yellow Kurla stone and white stones from Dhrangdra are the predominant materials used.The building has an area of 120,000 square feet (11,000 m²) and replaced the current Central Telegraph Office at Flora Fountain as the new GPO. The chief feature of the architecture of this building is an ethereal central hall which rises up to the great dome. As the chief post office of the city, the post office handles huge volumes of mail and passes them on to other post offices in the city. The GPO has the Postal Index Number (PIN) 400 001. This GPO is having 101 counters. It also has a international philately section for enthusiasts.