Port Blair is the capital of the Andaman and Nicobar Islands, a union territory of India. It lies on the east coast of South Andaman Island and is the main entry point to the islands. It is home to several museums and a major base for the Indian Navy and the Indian Coast Guard and Indian Airforce. It is also the headquarters of the Tri Services Command. Port Blair is also famous for the historic Cellular Jail and other small islands which were once home to British colonists. The Cellular Jail, also known as Kala Paani (Black Water), was a colonial prison. The prison was used by the British especially to exile political prisoners to the remote archipelago. Many notable dissidents such as Batukeshwar Dutt and Veer Savarkar, among others, were imprisoned here during the struggle for India's independence. Today, the complex serves as a national memorial monument. The cancellation depicts Cellular Jail.