The Maximos Mansion (Greek: Μέγαρο Μαξίμου, Mégaro Maxímou) has been the official seat of the Prime Minister of Greece since 1982.

In 1916, Michalinos' widow, Irene Manoussis, after marrying banker and politician Dimitrios Maximos, sold the incomplete building to shipowner Leonidas Embirikos, only to re-buy it in 1921.

From the mid-1950s until 1982, the mansion was used as a guesthouse for important foreign dignitaries visiting Greece, including Marshal Tito of Yugoslavia in 1955 and Margaret Thatcher of the United Kingdom in 1980.

Papandreou himself rarely used it however, preferring to conduct his business from his family villa of Kastri (in the affluent northern suburbs of Athens), or from Lagonisi, where he spent the summer months.

The Maximos Mansion has the benefit of being located at the heart of Athens and very close to the Hellenic Parliament, but otherwise its use as the prime minister's office has been described as problematic in recent years, due to its rather small size; as a result, since the late 2000s, various proposals for moving the prime minister's office to a new location have been examined, with the Zappeion Palace considered the best possible solution.