Hidalgo Trading Company is a fictional warehouse used by Doc Savage.
☀As extravagant as The Shadows' sanctum was, it was nothing compared to Doc Savage's headquarters. In fact, Doc had not one, not two, but three different bases of operation. The primary one, and the only one known to the public was on the 86th floor of an unnamed skyscraper in New York City. Because there was only one building with that many floors in New York City in 1933 (when Doc Savage began publishing), it has most often been assumed that the unnamed skyscraper that was home to Doc's headquarters was none other than the Empire State Building itself, although this is never made explicit in the novels. Doc's 86th floor headquarters is reached by a high speed elevator accessible only to Doc, his aides, and his cousin Pat (sometimes Doc would try to find a way of locking her out, but she always figured out a way to get in). For added security, Doc also rented the 85th and 87th floors to keep people from spying on him. References are made to offices in floors other than the 86th which deal with such ordinary matters as security, correspondence, and so on.
Perhaps the headquarters of no other superhero or private eye was as well equipped as Doc Savage's 86th floor abode. It had sufficient accommodations not only for Doc and his men, but also several guests as well. It also had a fully equipped laboratory, a library with thousands of books, and a gymnasium. As might be expected, Doc's headquarters was protected by the same sort of gadgets which he uses on his adventures. Not only did Doc rent an entire three floors (and possibly others) of the skyscraper, but there was also a secret basement garage where Doc's various vehicles were located. Indeed, Doc not only owned cars, but planes, autogyros, boats, a submarine, and a dirigible. These were stored at another one of Doc's headquarters, a secret hangar on the Hudson River disguised as a warehouse belonging to "The Hidalgo Trading Company ." The secret hangar was accessed by a pneumatic tube system linked to the skyscraper where Doc's offices were.
Not only did Doc have three floors of what may have been the Empire State Building and a hangar, but his own hidden retreat as well. This was the Fortress of Solitude (if it sounds familiar, it because a certain comic book company ripped off the idea from the Man of Bronze...). Its whereabouts were initially unknown even to his aides and to his cousin Pat. It was here that Doc went for periods of time to develop new gadgets, conduct experiments, and engage in intense study. The Fortress of Solitude was located in a remote region of the Arctic. In the novel suitably entitled Fortress of Solitude, the Fortress is described as a "Strange Blue Dome." It is said that it resembled "...the perfectly spherical half of an opaque blue crystal ball--of incredible size, of course. It surface appears perfectly smooth, with no obvious openings, no doors or windows of any kind. It was made of an unknown substance, that was not glass or metal but resembled both." Within the Fortress of Solitude one can assume there were the same amenities as Doc's 86th floor headquarters--a laboratory, a library, and a gymnasium at least. Unfortunately it was also where Doc stored those gadgets which he thought were too dangerous for mankind to possess. This nearly led to disaster when his archenemy, John Sunlight, discovered the Fortress and stole two of these gadgets (in the aforementioned novel Fortress of Solitude), weapons with which he hoped to start World War II (keep in mind Fortress of Solitude was published in 1938).
Beginning with the 42nd issue of 181-issue Doc Savage Magazine (The Midas Man, Volume VII, No. 6, Aug 1936), Doc Savage's penthouse on the 86th floor of an unnamed New York City skyscraper (implicitly the Empire State Building) is linked to his Hidalgo Trading Company warehouse-boathouse-hangar on the Hudson River waterfront by pneumatic bullet-car nicknamed the Flea Run, Go-Devil and Angel-Wagon due to its hundred mile per hour speed and that plummets straight down from the penthouse ninety stories to a sub-basement, makes a 90° turn to travel a mile and a quarter (a little over two kilometers) 60 feet (18 meters) below 34th Street and then comes back up to ground floor of the warehouse, presumably at a shallower but still steep incline. The interior of the car is heavily padded, with four seats, one behind the other bobsled fashion. Since the car does not turn around, the seats are designed to rotate 180° so that the passengers always face in the direction of travel. The acceleration is such that, when traveling down the tube from the 86th Floor, no sensation of falling is experienced. The system is driven by enormous air compressors and compressed air receiver vessels housed on the roofs of both the skyscraper and the Hidalgo Trading Company.
From his collection stored in the Hidalgo Trading Company warehouse Doc uses a fast, silenced Motorboat, capable of self-righting itself after capsizing with a pop-up gun and tripod. The boat is described as being considered by the navy for the basis of "a fleet of light coastal defense speedsters" (similar to an armed Motor life boat in description). Last, and also from the warehouse, Doc again uses the Helldiver submarine (first seen in The Polar Treasure, June 1933). The Helldiver has many gadgets and experimental devices built into it. In this story the principle modifications are a mechanism to release a chemical similar to squid ink, external-viewing television screens and dial-based sonic devices allowing it to successfully navigate through New York harbour, and its traffic, while submerged.