Carthage Jail is a historic building in Carthage, Illinois, listed on the National Register of Historic Places (NRHP). It was built in 1839 and is best known as the location of the 1844 killing of Joseph Smith, founder of the Latter Day Saint movement, and his brother Hyrum, by a mob of approximately 150 men. It was added to the NRHP in 1973 and is operated by The Church of Jesus Christ of Latter-day Saints (LDS Church) as a historic site with an adjacent visitors' center.