BBD Bagh is locates just south of Howrah Bridge. Dalhousie Square which is renamed after Three Martyrs of Bengal, Binay, Badal & Dinesh was created in the heart of the imperial capital of Calcutta. The tank in the centre, fed by natural springs, is said to have supplied Charnock with drinking water. There are many historical buildings, which surround the square. The northern side is occupied by Writers' Building. To the east are commercial houses and the West Bengal Government Tourist Bureau. On the southern side is Raj Bhavan, residence of the Governor. Beside that are the State Legislative Assembly House and the Calcutta High Court. St John's Cathedral, which close to Raj Bhavan is the oldest church in Calcutta. On the western side is the imposing white domed General Post Office, next to which is the Reserve Bank of India building. Netaji Subhash Road is the centre of the onetime English commercial houses which today flourish in Indian hands. Lyon's Range stock exchange, behind Clive Street, is worth a visit for a glimpse of the frenzied dealing in shares, periodically erupting onto the street.