Amid the construction of the luxury Palazzo Naiadi Hotel, workers encountered a teeny problem not all too uncommon in the Italian capital: They were building a hotel on top of an ancient Roman bathhouse. 

In order to preserve the ancient structure, the construction team took a slightly revised course, and the bottom floor of the Palazzo Naiadi was changed to a museum of sorts. If you venture downstairs, you will be greeted to two spacious rooms with thick panes of glass on the floor, offering the surreal experience of looking down at ancient ruins below your feet. 

The baths date all the way back to the 3rd century CE. They were made of granite and marble slabs and filled with water piped in through metal pipes. The ancient structure is an octagonal shape, and is covered with engravings. Some are so old it is currently impossible to date them, while others were added after the bathhouse was finished in the Flavian Age.