The Presidential Palace is the residence of the President of the United States of Mexico. Although Sobel does not specifically say so, it is likely that the Presidential Palace was the old Viceregal Palace built by Hernan Cortés on the ruins of Moctezuma II's New Houses, on the east side of the Plaza Mayor, or Main Plaza.
During the Rocky Mountain War, the public reaction against President Pedro Hermión in the wake of the disastrous Battle of Williams Pass was so great that he was unable to leave the Presidential Palace without a large contingent of armed guards. After President Hector Niles signed the Hague Treaty ending the war, he became so unpopular that he was unable to leave the Palace at all for fear of assassination attempts.
In September 1881 President George Vining received a visit at the Presidential Palace from a delegation of Liberty Party members of the Senate led by Senate Minority Leader Thomas Rogers, who protested the abuses of the Constitution committed by Vining's Constabulary. Vining answered, "Have no fear of the Constitution. I have it here in the Palace, and will release it once peace returns to our land." However, by nightfall Vining was dead of a heart attack, and the Constitution would not be restored for another twenty years.
The Presidential Palace was renamed the Imperial Palace during Benito Hermión's brief reign as Emperor of Mexico. Hermión's reign ended when a force of Kramer Guards led by Commandant Martin Cole seized the Palace on the night of 16 October 1901 and cut off communications with the outside world. Hermión disguised himself as a servant and escaped, after which Cole proclaimed himself the provisional president of a restored U.S.M.
In For All Nails, Chapultepec Castle is the Presidential Palace.