Its origins are lost in the mists of time and my attempts to get definitive information about who built it and when has proven impossible.   Some say 4th, some 5th, others the 14th century.   What is certain is its importance to the Buddhists of Nepal and the many Tibetans who fled Tibet from 1958 and have built their community in exile around it.    One of the most important and largest Buddhist stupas in the world it has been a UNESCO World Heritage site since 1979 

For lovers of trivia:  Bouddhanath is also known as Khasti, or dew drops, as builders are said to have used dew to mix the mortar because of a  severe drought during construction

Postcards show Bouddhanath beautifully illuminated at night so we went late in the day.   Unfortunately that only happens on high days and holidays.  The moral of this story is buy a guide book, check the Internet before leaving home, or ask Uttam