The Old Custom House is a historic government building in downtown Cairo, Illinois. Built from 1869 to 1872, the building served as a customs house, post office, and courthouse. Alfred B. Mullett, the U.S. Supervising Architect at the time, designed the building in the Italianate style, a rarity among federal buildings; his design features a bracketedcornice and rounded windows. When Cairo built a new post office in 1942, the building became the town's police station. The building is one of the few surviving U.S. custom houses and one of the largest federal buildings of its era in the Mid-Mississippi Valley region.The site for the custom house was chosen in 1859 by Illinois Senator (and Abraham Lincoln’s opponent in the 1860 presidential campaign) Stephen A. Douglas. In 1866, John A. Logan returned to Congress and lobbied successfully for fifty thousand dollars to start construction, with fifty thousand dollars allocated each following year until construction was completed. Construction began in 1867, and the building opened to the public on the evening of June 16, 1872. The original purpose of the Custom House was to house the offices which dealt with collecting duties and tariffs on international imports which had not been offloaded before they reached Cairo on their way up the Mississippi River.