The telegraph services were introduced in Calcutta by the ruling British, with the basic intention of asserting more command over the law and order system in the country. Lord Dalhousie, the Governor-General of India from 1848 to 1856, initiated the modern postal service in India in the year 1854 and the Telecommunications began in the country for the use of the British East India Company, with the introduction of the telegraph in 1850, when the first experimental electric telegraph line was started between Calcutta and Diamond Harbour. However, the telegraph service was opened to the public in 1854.

Located on the southern side of Dalhousie Square, the Central Telegraph Office in Calcutta occupies two magnificent heritage buildings of Calcutta. Before 1757, the site of the CTO was occupied by a big tank, which was filled up by the owner, William Tulloh and the plot was occupied by his auction mart, Tulloh & Co. The firm used to auction everything under the sky, from horses to Indigo factories, even libraries. The advertisements of the company may still be found in many publications, like the Calcutta Literary Gazette. It is interesting to note that, William Tulloh, has been immortalized as Judas in Johann Zoffany’s painting of The Last Supper, which still hangs on the walls of St. John’s Church. The uniqueness of this painting is that Zoffany used real people from the fashionable Anglo-Indian society to portray Jesus and his twelve disciples and infamously auctioneer William Tulloh was used for Judas. Consequently, the painting incurred the wrath of Tulloh, who took objection to it and proceeded to the court of law against the painter. However, there is no documentary evidence about the alleged legal action.

Hindustan Bank, the first European style bank in India, started to operate their business from the premises in 1770. However, when the Government purchased the property, apart from the Hindustan Bank, many more commercial companies were in possession of the premises, which included the Burkinyoung, selling pianos and other musical instruments; F& C Osler, makers of fine glass chandeliers, candelabras etc; Mackillop, Stewart & Co, a mercantile house and John Prinsep.

The proposed building of the CTO was designed in 1868, by the Executive Engineer Barnfather with the assistance of Mr. Clark and the site was cleared in 1870. However, the construction of the building was delayed for the completion of the official ground work and after the plans and designs were revised by Mr Vivian, the construction of the eastern part of the red brick building started in 1873.The work was held up for a short while due to the famine of 1874 and finally completed in 1876. This eastern wing of the CTO, with a 120 feet tall bell tower, is popularly known as the Dead Letter Office.

The western wing of the CTO located adjacent to the Dead Letter Office Building and regarded as one of the most prominent surviving Victorian pieces of architecture in Calcutta, was built in 1914. Properly equipped with the technology of the time, telegrams, telephones & facsimile, it linked the city of Calcutta with the rest of the world. Today, the exquisite piece of architecture still continues to be used for storing and sorting out of the mail. Apart from that, it also serves as the local headquarters of the Bharat Sanchar Nigam Limited (BSNL), the state owned telecommunications services in India. However, the upper floors of the building have been converted into a guest house for postal employees, complete with kitchen, servants and enormous four poster beds.