Coliseum, Or Colisaeum Colosseum, an immense amphitheatre in Rome, the largest permanent structure of the kind ever built, standing near the centre of the ancient city, upon the spot once occupied by the reservoir of Nero, about 500 yards S. E. of the Roman forum, and 200 S. W. of the baths of Titus. Its ruins are still sufficiently complete to show the form of almost the entire structure, and are among the best preserved and most magnificent remains in modern Rome. The building was at first called the Flavian amphitheatre, the name Colosseum being first used some centuries later with reference to its immense size. It was begun by Vespasian, built by him as far as the top of the third row of arches, and finished by his son Titus, by whom it was dedicated in A. D. 80, with games, gladiatorial shows, and scenic exhibitions of unprecedented splendor, a great number of gladiators and several thousand wild beasts being killed in contests in the arena. The building, which covers nearly five acres, and in its complete state had accommodation for 80,000 spectators, is in the form of an ellipse; its longer diameter is 615 ft., its shorter 510; the height of its outer wall, where it is still entire, is 164 ft. The arena within is 281 ft. in length and 176 in breadth.
The exterior wall of the edifice consists of four stories, of three different orders of architecture; the first (lowest) is Doric, the second Ionic, the third and fourth Corinthian. The material was chiefly travertine for the principal walls, the spaces between being filled in with brick. The part of the Colosseum designed for spectators is in its leading features arranged like that in other ancient structures of the same design (see Amphitheatre); but the fact that in the ruin no traces are to be found indicating that the ranges of seats ever rose higher than at present, i. e., to the bottom of the third story, or half the whole height, has perplexed all antiquaries. It is hardly to be supposed that the whole upper part of the building, erected at immense expense, was added for no object but to increase the exterior height; yet, if the places for spectators never extended to a higher point than would appear from the remains now existing, the upper stories would seem to have been only useful for that purpose.
Various theories have been advanced on this subject; one of the most plausible is that the extra stories were in some way rendered necessary by the machinery of the velarium (awning or temporary roof) sometimes spread over the whole; another, that narrow galleries ran round the inner circumference of these upper walls; but this must remain a matter of conjecture. What was the position of the dens for the wild beasts used in the combats of the arena has been another vexed, question, as no traces of them are found; it appears probable, however, that they were situated under the podium, where they would open directly into the arena. - The best known events in the history of the Colosseum are those connected with the history of the Christian church. Many of the early Christians suffered martyrdom in its arena. St. Ignatius is said to have been the first, he having been given to the lions in this amphitheatre in the earliest days of Christianity. St. Potitus, St. Prisca, St. Martina, and many others, are recorded as having been put to death in the Colosseum in the 2d and 3d centuries, with hundreds of unnamed martyrs, of whom the only records remaining are notes of the number suffering together on the occasion of one festival or another.
A cross now stands in the centre of the arena, erected in memory of their martyrdom; and around the edge, close to the wall of the podium, are small chapels or stations, marking the stages of the Via Crucis, the devotional exercise of the Roman Catholic church commemorative of Christ's progress to the crucifixion. These devotions are still performed in the Colosseum on Friday of each week. Excepting the record of these martyrdoms, carefully compiled by ecclesiastical historians and undoubtedly largely mixed with tradition, the Colosseum finds singularly little mention in the works of ancient authors. The building is supposed to have remained entire until Rome was invaded by Robert Guiscard, who began its demolition to prevent its being used as a fortress. It served that purpose in the middle ages, however, and was long held as a stronghold by the family of Frangipani, until they were dislodged by their enemies the Annibaldi. In 1312 the muncipality took possession of it, and it was again used for public entertainments, especially for bull fights. In 1387 the canons of the Lateran were allowed to use it for a hospital. After the 14th century it began tp be despoiled by the great Roman families, who used its stone to build their palaces.
In the time of Sixtus V. it was proposed to turn it into a place of trade, erecting shops under the arcades; but the plan was unsuccessful. Clement XL endeavored to erect within it a manufactory of saltpetre, but he failed to carry out his design, and was persuaded to finally consecrate it to the memory of the martyrs, thus throwing over it a protection which preserved it from further injury.