Jethawanaramaya of Anuradhapura Kingdom (ජේතවන විහාරය)
Jethawana Stupa built by King Mahasen (276-303 CE) is the largest stupa in Sri Lanka. It was originally 400 feet (122 meters) in height and was the third tallest building in the world at that time. Even today as a brick monument, Jethawanaramaya still remains the tallest of its kind in the world.
