Lal Dighi, Artificial pond in B. B. D. Bagh, India

Lal Dighi is a rectangular pond with reddish-tinted waters located in the center of the B. B. D. Bagh business district in Kolkata. Colonial-era buildings and modern commercial structures surround it, defining the character of the city's historic center.

Lal Dighi existed in the village of Dihi Kolkata before Job Charnock's arrival. In 1709 its stagnant, algae-filled water was cleaned and turned into a sweet-water reservoir; under Warren Hastings the tank was cleared and its banks embanked. On 18 June 1756 the Battle of Lal Dighi saw the British East India Company defeated by Nawab Siraj ud-Daulah's forces, and Calcutta was lost until the British retook the city after the Battle of Plassey on 23 June 1757.

The name Lal Dighi is linked to Holi: after the colour games of Dol Purnima, the tank's water was said to turn red. Near the tank stood the kachari and Shyam Ray temple of the Sabarna Roychowdhury family, whose house the East India Company first rented and later bought.

The tank sits in the centre of B. B. D. Bagh, ringed by a railing, so the water itself cannot be touched or used. The state government built a 115,000 sq ft underground car park for 700 vehicles on the northern bank, in front of the Mahakaran secretariat, at a cost of 35 crore rupees.

The pond predates Job Charnock's arrival in Dihi Kolkata, and the Sabarna Roychowdhury family's kachari and Shyam Ray temple stood beside it; the East India Company first rented and later bought that house. In 1756 the Battle of Lal Dighi saw the British defeated by Siraj-ud-Daulah's forces, and Calcutta was lost until Plassey in 1757.