Notwithstanding the massive urban transformation of the Chaoyang district, a few architectural gems still remain. The vestiges of the 15C Ming fortifications, stretching for 1.5km, are a perfect illustration of this, including the defensive Southeast Tower, has resisted both time and the bulldozers. The tower is now home to one of Beijing's finest art galleries, the Red Tate Gallery; it has also preserved the graffiti carved in the brick by soldiers of the Eight Powers detained here in 1900, during the invasion of Beijing.