So much is historic about this hotel. Less than two weeks after its 1871 opening, the Palmer House burned to the ground in the Chicago Fire. Just two years later, it was up and running, making it the longest continuously operating hotel in America. The opulent Beaux Arts lobby showcases museum-worthy frescoes and displays a mural by 19th-century artist Louis Pierre Rigal. Even the brownies are inspired by history, made with a recipe invented by the hotel chef in 1893.