Andheri, Mumbai
A 65-million-year-old monolithic basalt outcrop in Andheri, formed by volcanic activity during the Deccan Traps eruptions that also shaped much of the Indian subcontinent. Its vertical hexagonal rock columns, similar in formation to Ireland's Giant's Causeway, make it one of only a few such geological formations found within a dense Indian city. A small temple sits partway up the rock and remains an active place of worship, though the summit itself has been closed to climbers since 2019 for safety reasons. It offers a rare, free glimpse of deep geological time in the middle of Mumbai's suburbs.