Caves Sepolcro di Atilia Pomptilla The tomb of Atilia Pomptilla, dates back to the first century AD and is known by many as the Viper's Grotto. It was called so for the decoration of the title page, which depict two snakes, a sign of conjugal fidelity. The cave was built by the Roman Lucio Cassio Filippo in honor of his wife, Atilia Pomptilla. The Cave is open to the public, and you can only see the tomb from the outside courtyard.