This commemorative stamp set issued by Vatican City in 1966 celebrates the Millennium of Christianity in Poland (966–1966). The designs honor important figures and events linked to Poland’s Christian heritage, including St. Wojciech (Adalbert) and the royal couple Mieszko I and Princess Dąbrówka, whose marriage helped bring Christianity to Poland. Architectural elements referencing historic Polish cathedrals further enrich the religious theme. Beautifully engraved with classic Vatican artistic detail, these stamps are prized by collectors of religious, historical, and Vatican philately. The issue represents both a spiritual and cultural milestone marking 1,000 years since Poland’s baptism.