Gilbert Hill Mumbai (Bombay)

Smack dab among the residential apartment blocks of Andheri (W) sits this 61m-tall black basalt mountain that resembles a chocolate molten cake (unsurprisingly, as it was formed as result of Mesozoic era molten lava squeeze – it's 66 million years old. Climb the steep rock-carved staircase for panoramic views and the two Hindu temples set around a garden. It's a rare geological occurrence that is similar to Devils Tower National Monument in Wyoming and Devils Postpile National Monument in California. It's a 1.5km walk west from Andheri station. Steel netting was installed in 2017 to protect ground level from falling rock.