According to tradition, Sestri Levante was founded by the Ligurian tribe of the "Tigullii" and it was already known in the Roman Age under the name "Segesta Tigulliorum". The ancient core of the town developed in the Middle Ages in a fortified position on the "island". After the 15th century, the town expanded onto the alluvial plain south of the Gromolo river. Sestri Levante then became part of the Fieschi family's domain, until it passed under the flags of the Republic of Genoa, which built the castle on the "island" and kept control of the town until the Napoleonic conquest.
In the 19th century Hans Christian Andersen sojourned here and was fascinated by the beauty of the place. Several important artistic and architectonic treasures stand out in Sestri Levante:
the 17th-century monastery of the Capuchins, with its beautiful wooden furnishings, built in one of the most charming points of the Baia del Silenzio (Bay of Silence); the medieval church of San Nicolò dell'Isola, dating back to the 12th century; the remains of the baroque Oratory of Santa Caterina, destroyed during the bombings of the Second World War; the restored palaces of Portobello (Villa Negrotto Cambiaso and the former Annunziata monastery) and the precious art collection at the Galleria Rizzi, besides all the historic villas belonging to important families of the Genoese aristocracy, who used to live here especially between the 17th and the 18th centuries.