ROME — Cats have prowled the streets of Rome since ancient times, more recently finding refuge with an association of volunteers who have lovingly tended to thousands of strays over the years amid the ruins of a site where Brutus is thought to have stabbed Julius Caesar in 44 B.C.

The shelter, in an underground space abutting a cherished archaeological site, consists of several bright, cage-lined rooms that hold dozens of strays at a time and has gained fame — and donations — as a popular tourist draw.

But after a couple of decades of tolerated, if not quite authorized, occupancy, Italy’s state archaeologists have told the association that it has to go, saying the illegal occupation risks damaging a fragile ancient monument. The cat lovers issued a ready reply: They have no intention of leaving.

“If they want war, we’ll give them war,” warned Silvia Viviani, a retired opera singer and one of the founders of the Torre Argentina Cat Sanctuary association. “The cats need us.”