Dongquan Lighthouse, also called Dongju Lighthouse, was built in 1872 to guide ships to Fuzhou when China was forced to open it and four other treaty ports to trade in the late Qing Dynasty. It was designated a second-grade historic site in 1988. Its body is made of granite. It rises 19.5 meters and casts a beam of light, diffracted through a crystal lens, that can be seen 16.7 nautical miles (about 31 kilometers) away. A unique feature of the lighthouse is a low, 30-meter windbreak wall that connects it with its office structure so that workers going between the two can bend low behind the wall during times of high wind to keep their kerosene lanterns from blowing out. The Lighthouse Museum, opened in the English-style building (which the locals call White-hair Castle) in June 2008, displays a rich collection of lighthouse artifacts that add value to any visit.