Gratiot Street Prison
The Gratiot Street Prison was an American Civil War prison located in St. Louis, Missouri and was the largest war prison in Missouri. Run by the Union Army, it housed Confederate prisoners-of-war. The prison building was previously a medical school named McDowell's College, which was confiscated by the Union Army and converted to a prison in December 1861. Its official capacity 1,200 but at times it had 2,000 prisoners.