Back in the 1960s, construction of an underground parking lot revealed a vast array of archeological ruins under the esplanade in front of Notre-Dame. Specialists were called in and the site was preserved and made accessible to visitors. The ruins are a jumble of centuries of Parisian history, including Roman baths, medieval ramparts, and an ancient port. Explanatory displays have been translated into English, but seeing as how it is difficult for even archeologists to make sense of the layers of stonework, spiffy 3D displays have recently been installed that show what Paris looked like during various epochs, bringing parts of the ruins to life. For some it’ll still be just a pile of rocks, for others, a fascinating look into the city’s history.