The Diocesan Museum named after Blessed Archbishop Antoni Julian Nowowiejski in Płock, established in 1903, is the first museum in the Kingdom of Poland founded by Fr. Antoni Julian Nowowiejski. Designed by architect Stefan Szyller, the museum initially collected artifacts related to Płock Cathedral and donations, including those from Fr. Tomasz Kowalewski and Prof. Franciszek Tarczyński. Between 1929 and 1930, the museum was expanded, and its collections were systematically enriched with valuable works of art, including manuscripts, medieval Masovian sculpture, goldsmithing, and liturgical vestments. In 2008, the museum moved to a new location in the former Benedictine abbey, and the building was consecrated by the Apostolic Nuncio, Archbishop Józef Kowalczyk. In its new venue, the museum displays rich collections, including an 18th-century herm of St. Zygmunt and several valuable chalices. The exhibition is divided into three thematic sections: Christ in Art, Christ in the Eucharist, and Christ in the Lives of Saints, and the museum's treasury is considered one of the richest in Poland. In 2009, the museum was named after its founder, Blessed Archbishop Nowowiejski. In the following years, it was managed by Fr. Bronisław Gwiazda, Fr. Stefan Cegłowski, and currently by Fr. Andrzej Milewski. Since 2008, the museum has organized exhibitions dedicated to modern sacred art and also features an amber collection that speaks to visitors through the richness of the region's history and culture.