The sixteenth century Rajon ki Baoli, or Well of the Masons. Built in the final years of the Delhi Sultanate, it's Delhi's most ornate step-well, and one of the main attractions at the Mehrauli Archaeological Park.
The Mehrauli Archaeological Park is perhaps Delhi's best kept secret. Containing ruins which, if one counts the foundation of the Hindu Rajput fort which underlies the whole area, date anywhere from the 8th to the 19th century, and encompass virtually the whole history of Islamic Delhi and then some, the park is among the very most fascinating places in the whole city. What's more, it's practically unknown.
