Digging in the area near the Western Wall, archaeologists have unearthed three connected subterranean rooms, which they have dated to sometime before the destruction of the Second Temple in 70 CE. Amanda Borschel-Dan writes:
The purpose of the three-room complex, hidden for centuries under a large 1,400-year-old Byzantine/Umayyad structure’s white mosaic floor, is still being investigated, but it may have served as a basement pantry, living space, or even a place to hide during raids—[perhaps] part of a much larger public structure that has since been obliterated.
Hewn out of bedrock using hand tools, including iron hammers, the three rooms are rather spacious, occupy different floors, and were connected by stairs.
[W]hile there are numerous contemporary ritual baths and graves that were also hewn out of rock during this era, this is the first example of what appears to be a living space. Inside the rooms, what looks to be niches for shelves and storage, as well as doorjambs and lantern niches, were chiseled into the bedrock.
Read more on Times of Israel: https://www.timesofisrael.com/in-first-2000-year-old-3-room-underground-complex-uncovered-near-western-wall/