Kourou, located on the mainland where the Kourou River flows into the Atlantic, was once the home of the "Kourou Prison," part of the infamous Devil's Island prison system. After the prison closed in the mid-1900s, most of the buildings were demolished to make room for the Hôtel des Roches. Among the remnants of the old facilities, the most noteworthy is the Dreyfus Tower, a small structure that resembles the leaning tower of Pisa, standing where the river meets the ocean. The original purpose of the tower was to communicate with the islands via the semaphore flag system in the days before radio. Remnants of the prison bakery also remain nearby.