
The ancient population of this region worshiped a god named Pen, identified with the most impressive mountain of the area, which took its name from that god : the Penna Mountain.
Around 150 BC the Romans took possession of the Valley, whose life, from then on, followed the ups and downs of the Roman Empire.
In the year 1164 Barbarossa made a gift of this feud to Obizio Malaspina, who built the Castle that still exists in the center of the town of Santo Stefano. In 1796 the Castle became the property of the Fieschi family and later on of the Doria family.
When the local population rose against the Doria domination, the region of Santo Stefano became the property of the Republic of Genoa, and then passed to the Kingdom of Sardinia, opening a period of commerce and smuggling.
The connection between the Doria Family with the town of Santo Stefano is visible in the parish church, where, on the high altar stands a painting showing the Madonna of Guadalupe, a gift that Cardinal Giuseppe Doria gave in 1814 to the believers of Santo Stefano. According to an ancient tradition this painting was on the ship of Andrea Doria during the Lepanto battle in 1571. The Madonna of Guadalupe is the patron of the town, and is festivity is celebrated on the first Sunday after the feast of Assumption (August 15th), with a Mass on the Maggiorasca Mountain.