One of the main attractions and trademarks of Argostoli is the lighthouse of Saint Theodore which is located on a man-made peninsula close to the Argostoli village. It is the most romantic spot in Kefalonia and it is highly recommended for taking photographs.

It is a unique circular structure, based on 20 white Doric architectural style columns and its tower is 8 m tall. It was built when Charles Napier was governor of Kefalonia, in 1928. Destroyed by the earthquake, it was rebuilt in 1964 according to its original architectural design, by Takis Pavlatos, a local architect.