Mount Othrys

Mount Othrys (Όθρυς in Ancient Greek) was the base of the Titans during the ten year war with the Olympian Gods known as the Titanomachy or First Olympian War and also during the Second Olympian War. It is made of black marble. It was assaulted by the Olympians, and then Zeus used Kronos's scythe to cut him into a million pieces, and then cast him into Tartarus. Mount Othrys is currently located on Mount Tamalpais in San Francisco.

The Titan's Curse
Percy and his friends saw Titan ruins on the mountain - which meant Luke was raising Mount Othrys.

The Battle of the Labyrinth
Mount Othrys was restored, with a Titan potato fortress on the top (where Atlas holds up the sky.)and it had Kronos living in it already.

The Last Olympian
Mount Othrys was fully restored, and so was Kronos (He possessed Luke's body). They were ready to take down Olympus. At the final battle, it was Annabeth, Grover and Percy versus Kronos. Luke then regained control of his body and asked Percy to give him Annabeth's knife, and with this knife, he stabbed himself in his Achilles' heel, which is under his left arm, therefore banishing Kronos. By doing this, Mount Olympus was saved.

Following the defeat of the Titans, Mount Othrys was reduced to rubble again.

The Lost Hero
It was revealed that the Roman demigods had assaulted Mount Othrys during the Second Olympian War and destroyed the palace. Jason, demigod son of Jupiter, was personally responsible for bringing down Mount Othrys' guardian Titan, Krios. The campers of the Greek Half-Blood Camp were led to believe that it crumbled due to the defeat of Kronos.