During the Middle Ages, the Flavian Amphitheater was first occupied by some civil dwellings obtained in the rooms of the annular corridors on the ground floor; then, in the 12th century, it was incorporated into the fortifications of the powerful aristocratic Frangipane family. It was a very extensive fortified structure, which united the Circus Maximus, the Palatine Hill and thirteen arches of the Colosseum on the side facing the Lateran. No trace remains of the medieval structures today, but these must have also occupied the second floor of the Colosseum. Presumably, however, the occupation was only external. The interior had suffered too much damage over the centuries: first the fires, then the earthquakes: in 442, 467 and above all in 476, the year in which it seems that Rome even shook for 40 consecutive days. The earthquakes followed one another in the following centuries (for example in 739 and 780), even if the first massive collapses seem to be attributable to the violent earthquake of 801, when the columns of the upper portico sank into the arena. With the earthquake of 1348 there was the enormous ruin of the part towards the Celio (and on that occasion there was a dispute between the Municipality, the Frangipane and the Pope over who should appropriate the fallen boulders).
The occupation of the interior of the Colosseum by calciners who adapted their homes and workshops in the monument dates back to the 10th century. The area was in fact also called Calcarium. Lime was obtained by burning both pieces of marble and travertine from the monument itself (already collapsed) and marbles from other sources. In the Middle Ages the famous holes were also made to extract the double dovetail metal lead grappas that joined the blocks in ancient times. As there was no concern on the part of anyone to rebuild where the collapses took place, the collapsed parts, usually the highest ones and the arches of the terraces close to the arena, became bare material and therefore real building resources for the most cunning entrepreneurs . It is also true that what the medieval Romans did against the Colosseum is nothing compared to the damage perpetrated by the Popes of the Renaissance: ashlars of the Colosseum we find them in the tribune of S. Giovanni in Laterano (1439) at the Basilica of S. Pietro (1451) in Palazzo San Marco (mid-15th century), in Ponte Emilio (1574). And finally, the most energetic looting dates back to the Baroque age, among which the most salient episodes occur in 1644 (when Pope Urban VI uses some blocks collapsed from three arches for the construction of Palazzo Barberini) and after the earthquake of 1703 (when the blocks are used for the construction of the Port of Ripetta).
Unlike many ancient monuments, in the Middle Ages the Colosseum was not involved in the process of renovatio christiana of ancient monuments, as for example it happened for the Pantheon (transformed into the church of S. Maria ad Martyres), the Temple of Antoninus and Faustina (which it was dedicated to S. Lorenzo), the Temple of Peace (of which a part became Ss. Cosma e Damiano) and so on. The Colosseum maintained its ancient and pagan air, which justified the birth around it of a whole series of legends, obviously unfounded, but which popular beliefs believed to be true.
A testimony of this mechanism can be found in a manuscript code of the Laurentian Library in Florence in which the work of Armannino da Bologna is reported. Also known as Armannino Giudice, this notary in 1325 composed the Fiorita, a collection of historical and legendary stories (in prose and verse), all enclosed in a moralistic frame. Now, Armannino, unaware that the Coliseo in Antico had been a place of spectacle, claimed that it was a temple, indeed the main one of the pagan temples around the world. In it would have been enclosed many diabolical spirits who performed great wonders, and the priests, showing the effigy of the main demon to the people, used to ask: Lo veneri ?, which in Latin was called Colis eum ?, whence the name of the building .. But apart from the etymology, this interpretation of the Colosseum as a demonic temple remains interesting; from it seems to depart a precise thread that connects the Fiorita with other medieval texts (such as an anonymous handwritten guide kept in the National Library of Florence of the early 15th century) in which it is stated that the Colosseum would have been a temple of the gilded bronze on whose surface all the stars were represented.
Source: http://www.medioevo.roma.it
