There really isn't any supreme building. Many Buddhist sangha's have their own temple, but there is no supreme temple. If there was one most important site for Buddhists it would be, of all things, a tree. The Bodhi Tree in Bodh Gaya is the place the Buddha sat under when he obtained enlightenment.
The Holy building for Buddhists is called a Temple.
Buddhists main rule is 'Not To Harm Others'
In a Supreme Creator.
Buddhists worship in a 'pagoda.'
The supreme court meets in the supreme court building.
Buddhists do not pray, they practice, and the theory is that they should practice everywhere, all the time, without limitation.
Ther eis no main country of Buddhists. Buddhists can be found in almost every country in the world. There is a larger concentration of Buddhists in East Asia (Nepal, China, Sri Lanka, Japan, Korea, etc) which is near to where The Buddha historically lived.
The main inscription on the front architrave is: "Equal Justice Under Law"; the one on the rear of the building says "Justice, the Guardian of Liberty."
Reincarnation
It was made to house the offices and court of the Supreme Court. That's why it is called the Supreme Court building.
Supreme Court Library Building was created in 1834.
A main place for a Buddhist to worship is in a temple called the Vihara. I hope this will help.