“Thalis o Milissios” is a specially built cable ship, constructed in 1909 on behalf of the American Government at Newport News Shipbuilding and Drydock Co., Virginia, with the original name of “Joseph Henry”.

This cable ship was transferred by the American Government to Greece in 1947 and subsequently delivered to the Greek Telecommunications Organization (OTE) and renamed “Thalis o Milissios”.

She was the first Greek Cable ship that undertook service for the laying and maintenance of telephone cables among the Greek islands.  During her service, until 1983 when she was laid-up, she laid 140 new cables and repaired more than 630 older ones.  “Thalis o Milissios” is the oldest cable ship in the world still maintaining her original steam engines.  She is also the first ship with high technical requirements, entered in the Greek Shipping Registry.

“Thalis o Milissios” is a floating telecommunications museum, since apart from being the oldest cable ship, she still maintains her cable-laying steam mechanism.  Moreover, much equipment representing the evolution of telecommunications from the beginning of the century such as radar, visual telegraphs, etc. can be found on board.