Buddha’s birthday falls on the first full day of the first month of the Hindu lunar calendar and is celebrated by Hindus as well as Buddhists. It is observed at Buddhist shrines and monasteries throughout Nepal, but a particularly grand ceremony is held at Buddha’s birthplace in Lumbini, on the Terai. In Kathmandu, the Tibetan enclave of Boudhanath is a particularly good place to watch the festivities.

Source: https://www.insidehimalayas.com/