English: Locust Grove is a National Historic Site and the last remaining place that Meriwether Lewis and William Clark stayed at west of the Appalachian Mountains during their famous exploration of the continent in 1804-06. Built in 1790, the site was originally owned by William and Lucy Clark Croghan, the brother-in-law and younger sister of William Clark and General George Rogers Clark, whom is buried on the property. The house is adjacent to Springfield, the home in which the 12th US President Zachary Taylor grew up, and is a Georgian-style brick structure that has been very well preserved. The house was later home to William Croghan's inheritor John C. Croghan, whom purchased Mammoth Cave in 1838 and had his slave Steven Bishop map the caves in 1844-45, which was the best map available of the caves until 1908, and included the Mammoth Cave System's connection to the Flint Ridge Cave System, which was flooded after construction of a dam and not rediscovered until 1972. Today, the house and grounds are a national historic landmark, which it was designated in 1986, and serves as a museum showing period artifacts and to tell stories of the Croghan and Clark families that lived and stayed in the structure in the late 18th Century and early 19th Century. The grounds are home to a number of accessory structures, including a smokehouse, kitchen, springhouse, barn, and several cabins and sheds, as well as a cemetery where the Croghans, George Rogers Clark and his wife, and Col. Jonathan Clark are all buried.