The co-cathedral of Sant'Eustachio martyr was built in XII century by the Norman feudal lord Roberto Gurgulione. It was rebuilt and enlarged around the second half of the sixteenth century by Count Alberto Acquaviva d'Aragona and today retains the Renaissance style. The façade is divided into three orders: in the central one it is possible to admire the magnificent rose window with sixteen arms richly decorated. On the central portal with an interrupted cusp erected by Corinthian style columns resting on stone lions, there is represented God the Father, under whom there is the lunette with the bas-relief with the scene of the conversion of the Roman general Eustachio. Inside, the basilica-cathedral features polychrome marble decorations made in the nineteenth century by Monsignor Giandomenico Falconi in 1560. The crypt, still covered with polychrome marble and stucco on the vaults, has three altars: on the right one in marble dedicated to Saint Eustace and his family, in the center a silver one dedicated to the Blessed Sacrament and on the left, again in silver, one dedicated to the Blessed Virgin Mary of Constantinople, patron saint of Acquaviva. This last altar preserves a painting of the Madonna of Constantinople attributed to Francesco Palvisino and dated between 1540 and 1560.