Samothraki was the first land where St. Paul set foot when he began his second missionary journey - the one in Europe from around 50 AD. According to the Acts of the Apostles, he spent a night on the island before departing for Neapolis (Kavala).
Acts 16:9: During the night Paul had a vision of a man of Macedonia standing and begging him, "Come over to Macedonia and help us."
Acts 16:10: After Paul had seen the vision, we got ready at once to leave for Macedonia, concluding that God had called us to preach the gospel to them.
Acts 16:11: From Troas we put out to sea and sailed straight for Samothrace, and the next day we went on to Neapolis.
Acts 16:12: From there we traveled to Philippi, a Roman colony and the leading city of that district of Macedonia. And we stayed there several days.
The saint rested on the northern shore of Samothraki, in Paleopoli. In 1938, the archeologists of the American School of Classical Studies discovered in the ancient city, close to the Towers of Gateluzzi, the ruins of an old church, built probably in remembrance of the apolstle's visit. It is believed to be one of the oldest churches in the world.
To mark the Saint's stay on the island, between 2007 and 2008 a monument called the Altar of Saint Paul (To Stasidi tou Apostolou Pavlou) was built. It's a semicircular structure with 6 columns and an inwards sloping roof made out of red tiles. In the center there is a panel with inscriptions in multiple languages telling the story of the Saint's coming to the island. On the sides there are four large mosaics depicting the event.
The Altar of St. Paul is 7 km away from Kamariotissa on the road to Therma, near the Tower of Gateluzzi from Paleopoli. There is no sign, just a car park on the right side of the road and a metal gate which might or might not be open. Fear not, you can go inside and take a peak. Just remember to close the gate behind you when you leave. Beyond the gate a short paved road leads to the monument.
Every year, on the 28th of July, in the eve of St. Paul's day, a religious service is held here, officiated by the Bishop of Alexandroupoli. The service takes place between 21:00 and 24:00 is attended by a lot of locals.