The Duchy of Athens, another of the Crusader States set up in Greece after the conquest of Constantinople’s Empire during the Fourth Crusade, encompasses the regions of Attica and Boeotia.

Occupying the Attic peninsula and extending partially into Thessaly, the Duchy had shared an undefined border with Thessalonica and then Epirus.

Athens was originally a vassal state of the Kingdom of Thessalonica, but after Thessalonica was captured in 1224 by Theodore, the Despot of Epirus, the duchy had become a vassal of the Principality of Achaea.

It does not hold the islands of the Aegean Sea, which are Venetian territories, but exercises influence over the Latin Lordship of Negroponte.

The buildings of the Acropolis in Athens serve as the palace for the dukes.

The first duke of Athens (as well as of Thebes, at first) was Otto de la Roche, a minor Burgundian knight of the Fourth Crusade, who had proclaimed himself "Lord of Athens."

Although he had been known as the "Duke of Athens" from the foundation of the duchy in 1205, the title does not become official until 1260.