The church, the refectory, the arcade, the meeting room, the passageway from the large cloister to the surrounding areas are all based on the original 13th century monastic design.

For those coming from outside, the church could be accessed through a low portico at the entrance.  The fathers reached the church through the arcade of the large cloister.  The entry has a white, veined marble framed door with corbels supporting a pointed lunette with a fresco executed by a follower of Niccolò di Tommaso between 1371 and 1374. In the fresco the Virgin and Child are surrounded by St Bruno, Queen Giovanna, St Giacomo and Count Arcucci who offers a model of his church to the Blessed Mother.  The single nave is rectilinear and divided into three spans by three pairs of pilasters which support beautiful pointed cross vaults with sharp corners.  The mullioned window with three lights at the far end was put in during the restoration of 1927 as a replacement for a large rectangular window.  It was modeled after an inlay from the Monastery of San Martino.  The rose window is 13th century.  The domes and walls contain remnants of late 17th century Baroque frescos and of the marble tombs of the Arcucci family now found in the former cathedral of Santo Stefano on Capri.  Further Baroque items include ornaments, relics and reliquaries (a particularly valuable one being that of San Costanzo by Pietro di Simone of Siena) and statues (including one of San Giacomo, by an unknown Neapolitan silversmith of the XVII century also now in Santo Stefano).  A receipt from the Archives of the Bank of Naples from the 1700’s tells us that two artists, Diodato Vespiniani and Francesco Mottola, painted pictures of the church for 300 ducats.
The fresco on the facing wall portrays San Giacomo at the battle of Clavijo at which—according to the History of Campostella--the Spanish fought the Saracens in 844.  The saint dressed as a knight appears on a white horse in front of the Spanish troops at the defeat of the enemy.  The date the fresco was painted is seen at the bottom as 1699.  The frescos of the sacristy narrate episodes in the life of San Giacomo:  The Vocation of San Giacomo, Jesus in the Garden of Gethsemani, the Transfiguration, the Beheading of San Giacomo.  The apostles are solemnly represented on the side walls of the nave and on the pendentives.  Later frescos on the apse represent the Trinity with a host of angels.  The San Giovanni Battista (St John the Baptist) dates from 1710.  The canvases at the sides of the transept—the Adoration of the Magi and an Episode in the Life of San Giacomo are by Nicola Malinconico and were painted between 1706 and 1708.  Those on the side wall of the nave are attributed to the same artist. There are seven canvases which portray Elias, Jeremiah, Abraham, David, San Costanzo, San Ludovico of Tolosa and San Giovanni Evangelista (St John the Evangelist).  The fact that these figures are represented here has always suggested they were commissioned, but who commissioned them remains unknown.