Santi Marcellino e Pietro al Laterano is dedicated to Saints Marcellinus and Peter, 4th century Roman martyrs, whose relics were brought here in 1256. The first church on the site was built by Pope Siricius in the 4th century, close to the Via Labicana's catacombs of Marcellinus and Peter, with an adjoining hospice which became a centre for pilgrims.
This church was restored by Pope Gregory III in the 8th century. In the 9th century, the remains of Saints Marcellinus and Peter putatively were transferred from the catacombs here to a church in Seligenstadt, Germany. When the church was rebuilt in 1256 by Pope Alexander IV, the martyrs' relics were putatively returned.
At Present, under the high altar is an urn containing relics of Saint Marcia. On the left side is an altar dedicated to the Blessed Virgin, with a copy of Guido Reni's The Virgin in Glory with Angels, St Joseph and St Rita. Next to it is the Chapel of Reconciliation. An image of the dedicatees was placed on the first column on the left from the entrance during this restoration, with an inscription recording the restoration. The hospice and church were then given in 1276 to the Confraternity of those Commended to the Saviour.
The present church is the result of Pope Benedict XIV's 1751 reconstruction. The present cube-shaped exterior is divided by pilaster strips in a Neoclassical style, but with a late-Baroque elements, including a dome influenced by the architecture of Borromini. The façade was designed by Girolamo Theodoli and the main altarpiece by Gaetano Lapis depicts the dedicatees' martyrdom. After that restoration, the church was awarded until 1906 for the worship of the Discalced Carmelites.
References:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.