The dedication is to St Nicholas of Myra.
The noble family of the Caetani were granted the ruined tomb by Pope Boniface VIII (one of the family) in 1299 and converted it into a castle by 1303, turning the tomb rotunda into a keep and adding ancillary buildings the ruins of which can still be seen.
Allegedly one of the motivations for this project was in order to extort tolls from passing travellers, and the nuisance that this cause was given as the reason why the Via Appia Nuova came into being to the east. Travellers simply created a new road, and left the original Appian Way to become the relic that it remains.
Foundation of church
The church was probably built for the use of the household as part of the original project, which was overseen by Francesco Caetani the cardinal of Santa Maria in Cosmedin. The pope granted a bull to his relative in 1302 giving him and his successors authority over the church, which was then actually in the diocese of Albano. According to a source given as Thomas of Celano (not the Franciscan, who was long dead), the architect was a Neapolitan called Masuccio.
There has been a little speculation on the original proposed function of the church, since a complex consisting of a castle with a monastery or friary next door is common in mediaeval northern Europe. However, here there is no archaeological evidence that any religious community was in occupation, nor any documentary references to support the idea. A strong resemblence of the architecture to that of early Cistercian monasteries seems to be the source of this, although the structure also resembles contemporary convent churches of the mendicant orders.
A surviving quotation from the lost bull mentioned above indicates that the church was originally intended to be parochial.
After the pope died, the complex passed to the Savelli family, and the name Capo di Bove (Ox's Head) is first recorded in 1314 when they were about to lose control. The Colonna and Orsini families succeeded to the property before the century was out.
At the end of the 15th century, the simple gabled façade was altered. An oculus was inserted at the top, and a small campanile built on the left hand side. The top of the frontage to the right of this was given a horizontal cornice.
The church only lasted as long as the castle did. The Orsini were not interested, and used it as a billet for retainers travelling to and from Rome. The date of abandonment was about the middle of the 16th century, since the Senate of Rome had to be persuaded not to order the demolition of the entire disused complex in 1589 in order to deny its use to robbers. Nobody seems to have recorded the date of deconsecration.
For the next two hundred years, the church was a sheep pen and the main entrance was blocked up to facilitate this use. Back then, there were no trees around the site and you have to imagine being able to see back down the hill to the city in one direction, and the short grass prarie of the Campagna all around. The sheep ruled.
The Torlonia family took over in 1797.
The ruins were overgrown and unkempt until the end of the 19th century, but the complex was then sequestered by the State in 1904. Antonio Muñoz had the church fabric consolidated in 1909, by which time the walls had crumbled dangerously near to the tops of the windows. He inserted brickwork into the latter, rebuilt the tops of the walls and also the apex of the campanile.
Further work has been done recently, which included unblocking the main entrance. The church is now very tidy with an information board, although visitors are not allowed into the interior.
In 2013 the church was the venue for an exhibition of bronzes by the Columbian sculptor Fanor Hernández, entitled Materia e Vita.
The plan is basically rectangular, but some surveys (certainly not all) have spotted that the façade is at a slight angle to the main axis. The right hand side wall is longer than the left.
The single nave has seven bays of equal length, and a segmental apse.
The nave dimensions are 21.5 metres by 9.4 metres.
The church is a very rare example of the use of the mediaeval Gothic style in Rome. In fact, the only other one is Santa Maria sopra Minerva, and that was because the Dominicans who built it came from France. It is a minor mystery as to why the style was chosen here. Two possibilities is that the founder simply liked the style, or that a very cheap Gothic building would look better than a very cheap Romanesque one.
The seven nave bays are identically treated, except the fourth one. Each bay has an identical Gothic single-light window on each side, and externally is separated from its neighbours by external solid pilaster buttresses with sloping tops. There are buttresses at the corners of the nave too, making a total of sixteen of them.
Internally, you can see settings for transverse stone arches separating the bays, and these would have supported the vanished wooden roof. The arches sprang from corbels carved to resemble tulip flowers, and these are the only sculpture surviving in the church.
The fourth bay has a side doorway in its left hand wall. You can see that the farmer converting the ruin into a sheep pen blocked half the width, so that only one sheep at a time could get in or out.
The apse has a large conch, and a simple string course separates it from the curved wall below. It never had windows. There is a small niche with marble lining here, which seems to have been an aumbry or holy oil cupboard.
The back wall had a horizontal top, meaning that two triangular sections stood out over the sloping nave roof at this end.
The façade is unadorned, except for an oculus (porthole window) high up. If you could get into the church (for which you would need special permission), you will see that this window was inserted in the gable of the original façade, but not below the original apex. It is slightly displaced to the church's right. Also, if you look closely you will see that the original window which occupied the oculus was octagonal.
This oculus, the campanile and the horizontal piece of walling to the right of the bellcote were added in an unrecorded restoration of the church in the late 15th century. Again, this is all obvious in the inside view.
The campanile, or bellcote, has two round-headed opening pierced through where the pair of bells would have hung.
The main entrance door used to be walled up until very recently, but is now unblocked. It has a lintel made out of a fragment of ancient architrave, with a shallow relieving arch in the fabric above which has not prevented its cracking. This lintel rests on two carved limestone blocks which seem anciently to have been parts of ancient colonnettes.
Most of the edifice is built out of tufo blocks, mostly quite neatly cut and laid, with the roof arch springers using a better quality (peperino di Albano). The string course of the apse is in sandstone.
The blocking material of the doorways has its own interest, as the farmer who did it obviously used what he had to hand. The main door used to be blocked with grey sandstone rocks very badly laid, but the partial blocking of the side door includes fragments of high-status marble (scaglia).
The tops of the windows show modern restorative brickwork. The window frames themselves are of high-quality limestone. The arch conch contains much brickwork, using ancient bricks.