Calcutta is one of the largest cities in the world. It's the capital city of the Indian state of West Bengal. The city is sandwiched between the river on the west, the salt lakes to the east and the marshes and the swamps to the south. The region is part of the world's largest deltaic zone at the mouths of the river Ganges. The famous Sunderban mangrove forests are to the south of the city. The main city has a huge open area known as the Maidan. Most of the city's important landmarks, commercial areas and localities have come up around the maidan. The important roads here are the Chowringhee Road, Park Street, Shakespeare Sarani, Camac Street and the AJC Bose Road. The south of Park Street area is the main business address of the city. Kolkata's most famous building - the Victoria Memorial Hall is at the southern end of the Maidan. Greater Calcutta is a massive mixture of urban and semi urban sprawl. The best time to visit Calcutta is between the months of October and March when its cooler than the rest of the year. This is also the best time to visit India. It is sweaty during the summer (May - Jun) months. The monsoons (Jun - Sep) sometimes bring in heavy rain which can throw the city out of gear. All said and done, Calcutta's weather is moderate compared to the extremes in other parts of India. Calcutta's famous Durga Puja festival is held sometime in September or October (depending on the Hindu religious calendar).