Patee House served as the Pony Express Company's eastern headquarters from April 3, 1860 to September 13, 1861. The company's official name was The Central Overland California and Pike's Peak Express Company. John Patee built the hotel from 1855-1858 at a cost of $180,000. When new, the four-story building was the largest hotel west of the Mississippi River and one of the finest in the world, with gas lights, running water, and flush toilets. Its main entrance faced north on Penn Street, and on the hotel's north side by the northwest corner, a door was used by Pony Express riders and horses to pick up mail inside the building. Riders who did not live nearby stayed at Patee House.