The longest river in India, sacred to the Hindus to whom every drop is akin to holy water, the magnificent Ganges runs roughly west to east across the top of India from the Himalayas across the northern Indian plains to the Brahmaputra Delta on the Bay of Bengal. If you keep an eye on the water you may be able to spot India's national aquatic mascot, the Ganges river dolphin, not to mention turtles, walking catfish and crocodiles, while overhead in the trees you should look out for kites, partridges, myna birds and parakeets.
Formerly Calcutta (until 2001) and capital of West Bengal, this city is one of the cultural and economic powerhouses of India, and hosts scientific institutions, art galleries, museums and addas, a uniquely Kolkatan type of debating forum.
If you're up for a rickshaw ride, sites not to miss here are the Victoria Memorial, St Paul's Cathedral, the city trams, South City Mall, Dakshineswar Kali Temple, and Vidyasagar Bridge.
This holy city was the birthplace of the 16th century spiritual leader and founder of the Hare Krishna movement, and is now visited by around a million pilgrims every year.
Located around 130km north of Kolkata at a point where the Ganges meets the Jalangi river in West Bengal, Mayapur has a pleasant laid-back air and lots of beautiful temples.
Varanasi "is older than history, older than tradition, older even than legend, and looks twice as old as all of them put together", said Mark Twain in 1897. Located in Uttar Pradesh in the north east of India, this multi-religious hub is considered to be the holiest city in both Hinduism and Jainism, as well as being pivotal in the rise of Buddhism as the place where the young Siddhartha gave his first sermon. Shiva worship also has its roots here, as does Sikhism, so it's not altogether surprising that there are an estimated 23,000 temples here.
There are 15 mosques too, and a Mughal fort, a university and 19 special sites listed by the Archaeological Survey of India.
Varanasi doesn't just live in the past though, and is today one of the global UNESCO Cities of Music, and holds regular festivals visited by thousands.