Leavenworth Penitentiary, officially known as the United States Penitentiary, Leavenworth, is a high-security federal prison located in Leavenworth, Kansas. Established in 1903, it was the first federal prison built in the United States and has housed many notorious criminals over the years. The facility is known for its strict security measures and has a capacity to hold around 1,500 inmates. The prison is situated on a 600-acre site along the banks of the Missouri River. Leavenworth Penitentiary has played a significant role in the U.S. correctional system and has been the subject of various studies and documentaries. Its historical significance and architectural design make it a notable landmark in Kansas.