Kathmandu lies in a basin characterized by a generally flat and gently undulating terrain, sitting at an average elevation of 1,400 meters (4,600 feet) above sea level. The topography is predominantly a bowl-shaped depression, formed by the draining of a paleolake millions of years ago, which left behind thick, fertile lacustrine (lake) deposits.
The highest points surrounding the valley reach upwards of 2,700 meters, with Phulchowki being the highest peak on the valley rim at 2,782 meters (9,127 feet). The lowest point in the valley is the Chobhar Gorge, located in the southwest, where the Bagmati River exits the basin at an elevation of roughly 1,140 meters (3,740 feet).
Within the city itself, the terrain is relatively flat but gently slopes down towards the river corridors. The flood plains of the Bagmati and Bishnumati rivers represent the lowest-lying areas within the urban footprint, making them historically vulnerable to monsoon flooding, a situation exacerbated by modern encroachment on the riverbanks.