Delhi Ridge

The rock underfoot is about 1.5 billion years old, which makes the Himalayas, at roughly 50 million, the young range in the room. This is the northern tail of the Aravallis, quartzite and modest in height, running some 35 kilometres from Tughlaqabad and the Bhatti mines in the south east up to Wazirabad on the west bank of the Yamuna. It keeps the hot winds off the Rajasthan deserts, and it is the reason Delhi is the second most bird-rich capital in the world, behind Nairobi. Go early and pick one stretch; nobody walks the whole 35 kilometres.