NYC BIN

The Building Identification Number is assigned by the New York City Department of Buildings and ties a building to its entry in the city's own records.

Seven digits, and the first states the borough: 1 Manhattan, 2 the Bronx, 3 Brooklyn, 4 Queens, 5 Staten Island. The remaining six number the building within that borough.

A number ending in 000000 after the borough digit is a placeholder the city assigns to a tax lot that has no building recorded on it, so such a value identifies a parcel rather than a structure.

The number belongs to the building and the NYC BBL to the lot it stands on. One lot can carry several buildings, each with its own number, which is why the two fields are separate and neither can be derived from the other.