The monument zones are situated within the Kathmandu Valley, a large, bowl-shaped basin in central Nepal. The valley is surrounded by four major mountain ranges: Shivapuri to the north, Phulchowki to the south, Nagarjun to the west, and Chandragiri to the southwest.
Geologically, the valley was once a massive prehistoric lake. The ancient lakebed left behind highly fertile alluvial soil and clay, which historically provided the essential materials for the region's famous brick and terracotta architecture.
The Bagmati and Bishnumati rivers flow through the valley, serving as vital ecological and spiritual arteries. Many of the most sacred monuments, such as the Pashupatinath Temple, are built directly on the banks of these rivers, which are central to Hindu cremation rituals and daily purification ceremonies.