Federal Reserve Bank of New York: More than 20 metres below the ground, the building is situated in the world's largest "gold treasury" with a total value of more than $400 billion in currency and gold, and it is an absolute treasury. The entire underground vault is about half the size of a football field, surrounded by the hard rocks of Manhattan Island. The extraction of gold must be supervised by a three-person team, which belongs to the accounting, management and security departments. Each warehouse has three locks, which must be opened by the three people separately. Little known is that the Treasury does not even have a "gate" to the outside world, and can only be accessed through a 90-ton steel machinery. There are many such information boards on the streets of New York, introducing relevant information for tourists.