Santi Martiri church was founded adjacent to a Benedictine abbey in the 10th century but was rebuilt over the centuries. The church held custody of the Holy Martyrs, patrons of Arona. The present church has a Baroque façade added by the Jesuits, who were assigned the church and monastery by Cardinal Carlo Borromeo in 1572 and remained till their suppression in 1773.
The interior retains gothic elements of architecture and consists of a single nave with four lateral chapels. The fresco decoration was added between 1850 and 1852.
The main altar has a 15th-century painting depicting an Enthroned Madonna between Angels and Saints by Ambrogio da Fossano, called il Bergognone. The church also has a painting by Palma il Giovane. The altar has bas reliefs depicting the four Martyrs, whose relics are sheltered here.
References:The church of the former Franciscan monastery was built probably between 1515 and 1520. It is located in the UNESCO World Heritage Site of Old Rauma. The church stands by the small stream of Raumanjoki (Rauma river).
The exact age of the Church of the Holy Cross is unknown, but it was built to serve as the monastery church of the Rauma Franciscan Friary. The monastery had been established in the early 15th century and a wooden church was built on this location around the year 1420.
The Church of the Holy Cross served the monastery until 1538, when it was abandoned for a hundred years as the Franciscan friary was disbanded in the Swedish Reformation. The church was re-established as a Lutheran church in 1640, when the nearby Church of the Holy Trinity was destroyed by fire.
The choir of the two-aisle grey granite church features medieval murals and frescoes. The white steeple of the church was built in 1816 and has served as a landmark for seafarers.