The Mendelson Building occupies most of the block on the west side of Broadway between Fourth Avenue and Vine Street.
To the east, between Broadway and the Hudson River, are parking lots, vacant land and another large building.
Two other industrial buildings, of a similar size and shape but not as old, are to the north.
A modern warehouse is on the south.
On the west are railroad tracks used by CSX and the elevated roadways of Interstate 787, dividing the waterfront from the residential neighborhoods of the South End.

The building itself is a three-story 10-by-13-bay brick structure on a foundation of cut bluestone and topped by a flat roof.
The facade bricks are laid in common bond.
Most windows are 12-over-12 light wood double-hung sash windows with mild segmental-arched lintels.
Smaller, narrower windows are interspersed between them at irregular intervals, most significantly on all three stories between the fourth and fifth bays from the east on the north side.
A small round window is on the third bay south on the east side.

A belt course connects the window lintels.
These are the building's only decoration besides "Port Business Center" painted in large black letters on a yellow background just below the eastern roofline.
The bricks rise several feet above the roofline to form a parapet capped with terra cotta barrel tiles.
At the southwest corner the roof is pierced by the elevator's motor housing, and a small chimney rises from the northeast.

In the fourth bay west from Broadway along the north side is the building's main business entrance.
A small set of steps leads up to a heavy wooden door with transom.
A similar secondary entrance is in the fourth bay from the east façade, just west of a large loading door similar to that in the middle of the east facade.
Along the south is a large metal canopy, and another loading door is in the center.
The west of the building has loading doors on the first and second floors.

Inside, the floor layout reflects both the temporary nature of industrial space and the cage structural system.
The building's structural load is carried by the steel beams and iron columns inside.
The exterior walls are self-supporting; corbeled pilasters on their interiors support the beams, and the iron columns are within the masonry of the building's two interior north-south firewalls.
Secondary support is provided by eight-inch–thick (20 cm) iron columns throughout.

The first floor is concrete.
On the upper two stories, 14-by-8-inch (36 by 20 cm) timber joists rest across the steel beams, supporting wood planking several inches thick.
This is covered by steel plate in many areas to make moving barrels around easier.
The firewalls have two entries with relieving arches and iron sliding doors on tracks.
The elevator in the southwest corner is the original traction elevator, with its motor on top to free up space on the first floor.
Most partitions within the firewalled areas are made of materials that can easily be removed without seriously damaging the building.
The Mendelson Building occupies most of the block on the west side of Broadway between Fourth Avenue and Vine Street. To the east, between Broadway and the Hudson River, are parking lots, vacant land and another large building. Two other industrial buildings, of a similar size and shape but not as old, are to the north. A modern warehouse is on the south. On the west are railroad tracks used by CSX and the elevated roadways of Interstate 787, dividing the waterfront from the residential neighborhoods of the South End.
The building itself is a three-story 10-by-13-bay brick structure on a foundation of cut bluestone and topped by a flat roof. The facade bricks are laid in common bond. Most windows are 12-over-12 light wood double-hung sash windows with mild segmental-arched lintels. Smaller, narrower windows are interspersed between them at irregular intervals, most significantly on all three stories between the fourth and fifth bays from the east on the north side. A small round window is on the third bay south on the east side.
A belt course connects the window lintels. These are the building's only decoration besides "Port Business Center" painted in large black letters on a yellow background just below the eastern roofline. The bricks rise several feet above the roofline to form a parapet capped with terra cotta barrel tiles. At the southwest corner the roof is pierced by the elevator's motor housing, and a small chimney rises from the northeast.
In the fourth bay west from Broadway along the north side is the building's main business entrance. A small set of steps leads up to a heavy wooden door with transom. A similar secondary entrance is in the fourth bay from the east façade, just west of a large loading door similar to that in the middle of the east facade. Along the south is a large metal canopy, and another loading door is in the center. The west of the building has loading doors on the first and second floors.
Inside, the floor layout reflects both the temporary nature of industrial space and the cage structural system. The building's structural load is carried by the steel beams and iron columns inside. The exterior walls are self-supporting; corbeled pilasters on their interiors support the beams, and the iron columns are within the masonry of the building's two interior north-south firewalls. Secondary support is provided by eight-inch–thick (20 cm) iron columns throughout.
The first floor is concrete. On the upper two stories, 14-by-8-inch (36 by 20 cm) timber joists rest across the steel beams, supporting wood planking several inches thick. This is covered by steel plate in many areas to make moving barrels around easier. The firewalls have two entries with relieving arches and iron sliding doors on tracks. The elevator in the southwest corner is the original traction elevator, with its motor on top to free up space on the first floor. Most partitions within the firewalled areas are made of materials that can easily be removed without seriously damaging the building.
A. Mendelson and Son Company Building