About 55 million years ago a great burst of volcanic activity spread out from where is now Madhya Pradesh in NW India. It was one of the major volcanic events in geological history, spreading more than a hundred layers of basalt over the region every ten thousand years or so. You can see two of the layers, or Traps, on the horizons in the pictures, forming a 600m surface above sea between Mumbai and Delhi.
In the early 1400s Afghan muslims used the basalts to build mosques on the Deccan, like these examples from Mandu, 50kms south of Indore. Later, pillars in the Hindu style were added to nearby temples and included pink limestone pillars thought by some to have been brought from Rajasthan by elephants.
Most of the buildings were for the Moghul Emperor Humayan around 1534 and then from 1550 for the Moghul Emperor Akbar. One of the centre-pieces is the 1659 Hoshang’s tomb of marble. Many other buildings were made from the Deccan basalts until 1732, when the end of Mandu’s active years began. Now all the buildings are deconsecrated and open to tourists.