According to Swayambhu Purana, the Kathmandu Valley was once a large lake "Nagedaha" (Sanskrit: Naga Dah menas "Snake Lake"). Legend says, and many believed that Manjusri (Sanskrit name मञ्जुश्री [Mañjuśrī] can be translated as "Gentle Glory", Chinese 文殊菩薩, a bodhisattva associated with transcendent wisdom), saw a lotus flower in the center of the lake and cut a gorge at Chovar to allow the lake to drain. The place where the lotus flower settled became Swayambhunath Stupa and the valley thus became habitable.
Here is a crop from the center of the panoramic image above, so it shows a little more detail on web. However, anyone wants to have an idea of what detail on the original art, contact me.