Located right outside the elegant Hofburg Palace, Michaelerplatz is Vienna’s most popular square, always teeming with tourists and horse-drawn carriages. But its under-appreciated historic attraction is hidden in plain sight, smack in the middle of the plaza.

The archaeological complex, now known as the Ausgrabungen or “excavations” of Michaelerplatz, is a time capsule preserving a wide range of Viennese history that spans no less than 1,500 years, from the Roman Imperial times to the 19th century. It was laid out by renowned architect Hans Hollein as part of the Wien Museum after the ruins were unearthed in 1990, displaying the remains of several bygone structures.

The oldest ruins date all the way back to the second to fourth centuries, when the city of Vienna was still known as a Roman legionary camp called Vindobona. This includes the remains of ancient canabae, a military settlement built on the fortress. On top of those ancient structures, there are Renaissance-period walls that once enclosed the palace’s “Paradise Garden” and the foundations of residences from the seventeenth, eighteenth, and nineteenth centuries. These will, quite certainly, give you a glimpse into the rich history of Vienna’s past.