An abandoned temple at the foot of Vesuvious. It is home to the Roman hermit, Lucius Caelius. The temple soon became the base for Spartacus' rebels during season 2 and used as their own command post.
The temple comes under siege by the forces of Rome, first by Publius Varinius, whom the rebels defeat, and then by Gaius Claudius Glaber and his army. Glaber succeeds and forces the rebels to retreat to the top of Mount Vesuvious and turns the temple into his own base of operations.
The rebels later reclaim the temple and defeat Glaber's forces for clever means. The temple would then remain that as the place of victory for the rebels over two Praetors of Rome and marked their ascent to a real army and a real threat to the Republic.