Situated at the head of the dock between Long and Central Wharves, fronts east on the dock, west on India Street, and is in the form of a Greek Cross, () the opposite sides and ends being alike. It is long north and south, wide at the ends, and through the centre. It is built on about 3,000 piles, fully secured against decay; the construction throughout is fireproof and of the very best kind.
The exterior of the building is purely Grecian Doric, not a copy, but adapted to the exigencies and peculiarities of the structure, and consists of a portico () of 6 columns on each side, on a high flight of steps, and an order of engaged columns around the walls, 20 in number, on a high stybolate or basement; the order of engaged columns terminating with 4 andae () at their intersection with the porticos. The columns are in diameter and high, the shaft being in one place, each weighing about .
The cellar, which is high to the crown of the arches, is principally used for the storage of goods, which are conveyed to it through the basement story. The steam apparatus for warming the whole building (which it does effectively) is situated in the cellar, having easy access to the coal vaults under the sidewalk outside of the building.
The principal entrances to the basement story are at each end. They are for the receipt of goods for storage. Near the northwest corner, on the west side, is the entrance to the Night Inspectors' apartments, also to the private staircase leading to the Collector's room and the attic. South of the west portico is the entrance to the heating apparatus room, and on the south end is the entrance to the Custom House Truckmen's room. This story consists of rooms for the Night Inspectors, Custom House Truckmen, and Engineer of the Heating Apparatus, also three sets of Water Closets: the remainder is used for storage of goods, weigher's tabs, etc.
The principal ingress to the entrance story is through the porticos, but it can be entered from the Collector's private staircase, and from two other private staircases in the basement. This story contains apartments and offices for the Assistant Treasurer, the Weighers and Gaugers, the Measurers, Inspectors, Markers, Superintendent of Building, etc. In the centre is a large vestibule, from which two broad flights of steps lead to the principal story, landing in two smaller vestibules therein, lighted by skylights in the roof, and these vestibules communicate with all the apartments in this story. The several rooms are for the Collector, Assistant Collector, Naval Officer, Surveyor, Public Store Keeper, their Deputies and Clerks; and for the facilities of doing business this arrangement is not surpassed. The grand-cross shaped Rotunda, for the general business of the Collector's department, in the centre of this story, is finished in the Grecian Corinthian order; it is in its greatest length, 59 feet wide, and in the skylight.
In one of the panels of the Rotunda is inserted a tablet of marble (Dedication Tablet 1847), containing the following inscription: Boston Custom House Building. Authorized by the 23d Congress, A.D. 1835. Andrew Jackson, President U.S.A.; Levi Woodbury, Sec'y of the Treasury.—Opened August 1st, A.D. 1847, James K. Polk, President U.S.A.; Robert J. Walker Sec'y of the Treasury; Marcus Morton, Collector of the Port; Samuel S. Lewis, Robert G. Shaw, Commissioners; Ammi Burnham Young, Architect.