The two rulers concluded a treaty of alliance, by which John de la Roche's brother and heir, William, would marry John Doukas's daughter Helen and receive the fortresses of Gravia, Siderokastron, Gardiki and Lamia as her dowry.
The municipal unit Gravia is situated in the foothills of the mountains Giona and Parnassus.
Sklithro, Phocis, a village in Phocis, part of the municipal unit Gravia
Gravia |