“Castles” is the theme chosen for the member countries by PostEurop for Europa joint issues 2017. The €0.95 value shows the Second Tower of San Marino, called Cesta, situated on the highest point of Mount Titano, 755 meters above sea level. It was an ancient Roman watchtower and in 1956 it became the seat of the Museum of Ancient Arms. The €1.00 value shows the First Tower, named Guaita, which is the major and most ancient of the three rocks, dating back to the 11th century.