Foreigners' Street was an amusement park, including the Porcelain Palace, the world's largest toilet. Also the location of the abortive Love Land development in 2009. The Black Mountain Valley (Heishangu).[146] Hongya Cave (aka Hongya Dong), a pier stilt house fortress that served as one of the 17 city gates of Ancient Chongqing is a popular tourist attraction for its architecture.