The Ithomi was an ancient fort in the region of Messinia, in south-west Peloponnese. At the top of the homonymous mountain at a height of 805 meters. The mountain was dedicated to Zeus the Ithomata because of several lightning bolts that fell there, and was on top of an altar.
The fortress of Ithomi played an important role in A' Messinian War in the late 7th century BC, between Messenia and Sparta.

The fort was the last bastion of Messinia and was finally leveled after a heroic siege. In the next few years Ithomi had a symbolic role at the heart of conquered Messenia.
In 464 BC after a devastating earthquake in Laconia enslaved Messenians revolted, fleeing again to Ithomi, rebuilding fortifications and then resisting for many years before surrendering. With the support and assistance of the Athenians they settled in Nafpaktos.

After the victory of Athens over Sparta in 426B.C at Pilos and Sfaktiria a lot of Messenians settled there. Perhaps that was when Nike of Paioniou was devoted to Olympia. The Athenian dominance in Pilos remained until 421B.C and then the Messenians were transported by the Athenians to settle in Kephalonia.
In 369 BC the Theban Epaminondas at the Battle of Leuktra, liberated the area from the Spartan influence and chose Ithomi to build a new city, Messini.

www.toursingreece.gr/MessiniIthomi.htm 

 View photos from Archaeological site and Museum   1, 2, 3, 4