One-fourth of this magnificent building is taken up by an indoor ship dock. Shiny new boats of all types are moored at the dock. Among them is a tall schooner, an armored speed boat and a submarine berth. This held the Helldiver, an under-the-polar-ice submarine, until it was destroyed in the adventure of "Death In Silver."  By the time of "Quest Of Qui", a new experimental submarine that Doc is testing is stored here. 
 
In the hanger adjacent to the dock, is moored a large silver airship. The remaining area is taken up by aircraft of all type lined up in neat rows, with taxiways in between them. Many of the airplanes are fitted with pontoons. A ramp between the ship dock and the airship berth leads into the water. Ponderous doors let out into the Hudson River. At the rear of the structure the maintenance bays and offices are housed. The overhead is a maze of rolling cranes and steel catwalks. Everything inside the cavernous building is immaculate. 

The Hidalgo Trading Company building is first mentioned in the adventure of "The Lost Oasis". In addition to being fortified with concrete and structural steel walls, it possesses a security system that is far ahead of its time.  As Monk puts it, "A bird can't light on this building without us knowing it".