OSTIA. - A city and suburbicarian see in the province of Rome. With a decree of the Sacred Consistorial Congregation of 22 May 1948, the area of the diocese was limited to the ancient city and the castle of O. (AAS, 40 [1948], pp. 341-42). It has a population of 3,700 inhabitants gathered in one parish; it has a male and a female religious community.
At the Roman Council of 313, the bishop MAXIMUS was present (PL 8, 747); at the time of Pope Gelasius, the bishop was BELLATOR (494-95). Pope Eugene III in 1150 united the see of O. with that of Velletri, and it remained so until 5 May 1914, when Bl. Pius X with a *motu proprio* detached it again, assigning it to the Dean of the Sacred College (AAS, 6 [1914], pp. 219-20). Napoleon I, with a decree of 5 August 1810, had wished to suppress the diocese. Bishops of O. included popes: ODDONE DI LAGERY, later Bl. URBAN II (1088-99); LAMBERTO DI FAGNANO, later HONORIUS II (1124-30); UBALDO ALLUCINGOLI, later LUCIUS III (1181-85); UGOLINO DEI CONTI DI SEGNI, later GREGORY IX (1227-41); RINALDO DEI CONTI DI SEGNI, later ALEXANDER IV (1254-61); PIETRO DI TARANTASIA, later Bl. INNOCENT V (1276); NICCOLÒ BOCCASINI, later Bl. BENEDICT XI (1303-1304); STEFANO AUBERT, later INNOCENT VI (1352-62); GIULIANO DELLA ROVERE, later JULIUS II (1503-13); ALESSANDRO FARNESSE, later PAUL III (1534-49); GIAN PIETRO CARAFA, later PAUL IV (1560-65). In O., the Hieronymian Martyrology lists on 20 May AUREA (q.v.), whose *Passio* is without value (BHL, 810); on 16 July ILARNIUS, unknown; on 23 August CYRIACUS and ARCHELAUS; on 19 October ST ASTERIUS, mentioned in an inscription in the Lateran Museum (O. Marucchi, *I monumenti del nuovo Pio Lateranense*, Milan 1910, pp. 11, 28; the basilica of Asterius is mentioned in the *Libellus precum* [O. Guenther, *Epistolae imperatorum et pontificum*, etc. in CSEL, XXXV, II, p. 29], restored in 687 by Sergius II [Lib. Pont., I, pp. 376, 380] and later by Leo III [ibid., II, p. 14]). On 22 November and 22 December FELIX, DEMETRIUS, and HONORATUS are commemorated. According to the notice inserted in the biography of Pope Mark in the *Lib. Pont.* (I, pp. 80-81; 202), the bishop of O. had the use of the pallium and the right to consecrate the pope (q.v.). The anointing with oil in the consecrations of emperors was also performed by the bishop of O. The cathedral was originally the church dedicated to the apostles Peter, Paul, and John, attributed to Constantine in the *Lib. Pont.* (I, p. 183); then it was the church of St AUREA, which was already in poor condition and roofless at the time of Sergius I (687-701), who restored it (ibid., I, pp. 376, 380); Leo III (795-816) also repaired the roofs (ibid., II, p. 14); the building is also mentioned in the biography of Leo IV (847-55; ibid., p. 118). O. was devastated in 408 by Alaric, in 536 by Vitiges; Gregory IV enclosed it with walls (Gregoriopolis) around the year 830 (ibid., II, p. 164). The abandonment of O. is due to the loss of maritime and commercial traffic, which supplied the city of Rome. The silting caused by the Tiber amounts to about 4 m per year; at present the shore is 6 km from the ancient city. On 26 May 1159 the people of O., represented by a procurator, promised Pope Adrian IV to supply the Pontiff every year with two boats of wood, one for Christmas and the other for Easter, to be deposited at Marmorata or Ripa.
Archaeology. The first Roman military colony, the Castrum (Livy, I, 33; VII, 25; CIL, I, 2, p. 257), was founded around 335 BC (J. Carcopino, *Virgile et les origines d'Ostie*, Paris 1919). Its tufa walls, 5.40 m high (G. Calza, in *Notizie degli scavi*, 1914, p. 246; 1923, p. 178 ff.; T. Frank, in *Am. Journ. of Arch.*, 1918, p. 182), enclose a rectangle of 193 × 120 m within the imperial city. Legendary tradition traces the foundation of O. back to Aeneas (Virgil, *Aeneid*, VIII) and some ancient historians attribute it to Ancus Marcius (Dionysius of Halicarnassus, III, 44; Eutropius, I, 5; Festus, 1977; Cicero, *Rep.*, II, 5, 33; Servius, *Aen.*, VI, 816; St Jerome, *Chron.*, p. 334). The possibility of a pre-existing settlement before the Castrum is admitted by some modern historians such as Carcopino, de Sanctis, Frank, etc. Its position at the mouth of the Tiber, from which it takes its name (Strabo, III, 145; Livy XXII, 11), facilitated the rapid commercial development of the city, about 16 miles from Rome. Between 100-106 AD Trajan, with an audacious project, created the port of O. (Pliny, *Paneg.*, 29; Juvenal, 12, 75; *Notizie degli scavi*, 1925, p. 54), already begun by Claudius (Suetonius, *Claud.*, 20; Cassius Dio, 60, 11; Pliny, *Nat. hist.*, XVI, 76; XXXVI, 14), greatly increasing the importance of the city, which became the seat of vast annona, corporate, administrative, and religious organizations. Constantine deprived it of its municipal rights, assigning them to his port, which became "Portus Romae" ([q.v.] *Notizie degli scavi*, 1925, p. 73; CIL, XIV, 612). The Vandal invasion in 455 struck a severe blow to O., marking its decline.
Excavations carried out at intervals by Visconti, D. Vaglieri, and Prof. Guido Calza (1913-46) attest to the growing development of the city in its public buildings, dwellings, temples, warehouses, and road network. The very rich epigraphic collection gathered in the CIL XIV and in the supplement by Wickert (1930), with many other public inscriptions, by G. Calza, in *Notizie degli scavi* and in *Epigraphica*, and the Ostian Fasti published by A. Degrassi (*Fasti et elogia*, Rome 1937), added to an immense artistic heritage published by G. Becatti, R. Calza, G. Ricci, and M. Squarciapino, in *Bull. d’arte*, *Bull. comunale*, *Notizie degli scavi*, enhance the importance of O. for the study of classical antiquity (G. Calza, in *Pauly-Wissowa*, XVIII, II [1942], cols. 1654-64; R. Calza, *Scavi di O.*, *Topografia generale*, Rome 1952).
To these martyrs should be referred a small oratory of the 5th-6th centuries, built "in loco martyri" near the theatre discovered in 1910 (D. Vaglieri, in *Nuovo bull. d’arch. crist.*, 16 [1910], pp. 57 ff.; J. Carcopino, in *Journal des savants*, 9 [1911], p. 46; F. Fornari, in *Mélanges d’arch. et d’hist.*, 36 [1916-17], p. 37 ff.). In the oratory a 3rd-century sarcophagus was found, whose lid bears the Christian epitaph "Hic Quiriacus dormit in pace". A 12th-century manuscript, recently discovered by Fr A. Casamassa, attests that the place was still known.
Two other late-period structures, also located on the Decumanus Maximus (before reaching the Forum), one built in the shape of a Greek cross and the other where a small column with the figure of the Good Shepherd was found (G. Moretti, in Notizie degli scavi, 1920, p. 41; R. Calza, Museo ostiense, Roma 1947, no. 151), were likely used for Christian worship. Of great importance is the discovery of a large Christian basilica, complete with a baptistery (G. Calza, Un basilica di età costantiniana scoperta ad O., in Rend. Accad. pont., 1940, p. 63 ff.; ibid., 1941-42, p. 135 ff.). That the building was dedicated to Christian worship is confirmed by the inscription on the entablature above the entrance to the baptistery, which reads: *IN K GEON FISON TIGRIS EUFRATA CRI(STM)ARONUM SUMITE FONTES*. Calza, who attributed it to the 4th century, identified it as the basilica of SS. Peter, Paul, and John, donated by Constantine to the city of Ostia (Lib. Pont., I, p. 376). However, this dating has raised many reservations and objections, both because the capitals do not correspond to the period and because of the disjointed and modest construction, which is inconsistent with both the era and an imperial endowment (H. Fuhrmann, in Epigraphica, 3 [1941], p. 103 ff.; G. Becatti, Case ostiensi del tardo Impero, Roma 1948, p. 201). The hypotheses of A. V. Gerkan (Die christl. Anlage in O., in Röm. Quartalschrift, 47 [1939], p. 15-23), who suggests it was a catechumen school, and of Th. Klauser (Die Inschrift der neugefund. altchristl. Bauanlage im O., ibid., p. 25-30), who considers it a Christian library, lack convincing foundations. The dedication of the basilica remains an enigma, since among the known churches in Ostia, we must exclude that of St. Lawrence (Acta SS. Iunii, V, Paris 1867, p. 38), which was built “in porta” when it was called “Laurentia nuncupatur,” and that of Asterius, who was martyred with his companions “foras muros Ostiae civitatis.”
Beneath the west side of S. Aurea, the present basilica of Ostia, an apsidal chamber with tombs, characteristic of a Christian structure, has been uncovered. A precious discovery was the finding of a broken column, 70 cm high, bearing a fragmentary inscription of St. Aurea: *S. A R* with lettering from the 5th century, confirming the existence of the ancient church beneath the current one. In March 1945, in the adjacent courtyard, the memory of St. Monica, who died in Ostia in November 387 (St. Augustine, Confessions, IX, 8-12), was accidentally rediscovered; more than a third of the metrical inscription from her tomb, composed at the beginning of the 5th century by the proconsul A. Auchenius Bassus, has survived in about 12 manuscripts (A. Casamassa, in Rend. Acc. pont., 1945, p. 155 ff.).
Another Christian structure recently uncovered features a large apse built within the frigidarium of an Hadrianic-era bathhouse on the Via della Foce (G. Calza, Nuove testimonianze del cristianesimo ad O., in Rend. Acc. pont., 1949-51, p. 12), superimposed over a subterranean mithraeum. A *fucinus* (a type of lamp) was found standing on two small pillars within the chamber. A grand domus in the area of the Cardo Maximus on the Via della Caupona has a northern entrance adorned with a mosaic depicting a chalice with a fish; two more fish appear at the base of the cup (G. Calza, Nuove testimonianze, cit., p. 126 ff., fig. 3); another fish, carved into a large basin in the courtyard, led to the suggestion that it was used as a baptistery (G. Becatti, Case ostiensi, cit., p. 121). Around the chapel of St. Herculanus (adjacent to the present cemetery of Ostia), a striking 5th–6th century construction, about 100 inscriptions were found, supporting the hypothesis that this area was part of the ancient Christian cemetery of Ostia (G. B. De Rossi, in Bull. d'arch. crist., 1866, p. 49; L. Paschetto, O., Roma 1912, p. 180). These inscriptions bear the distinctive Ostian formula *“dormit in pace”* or *“cum Deus voluerit, volet, permiserit.”*
Other Christian relics from Ostia include several sculptures, sarcophagus fragments, and minor objects, such as a sarcophagus (similar to one found in the oratory near the theater) from the area of St. Herculanus with a Christian epitaph (P. E. Visconti, Dichiaraz. di un sarcofago in O., in Atti Pontif. accad., 15 [1864], pp. 159-71), nos. 1875, 1937, 1975, 2009-10a of CIL XIV and nos. 481029 (?), 5204 (?), 5232-41, 5312 (?) from the supplement by Wicken to the same volume, and nos. 506, 525, 541, 558, 595, 617, 642, 649, 686, 746, 779, 801, 806, 821, 836, 840, 859 from the Magazzini di Ostia, among which a fragment, no. 506, depicts the resurrection of Lazarus (G. Calza, Nuove testimonianze, cit., p. 132, fig. 7). Two circular (or semicircular) marble slabs, of which only parts of the rims remain—one with fish motifs (no. 617) and the other with figures of the Apostles (no. 595) set within niches—may have been used for liturgical purposes or Christian agape meals. Another marble plaque (R. Calza, Museo ostiense, cit., no. 130), discovered in 1939 in a kind of public hall surrounded by benches and pillars, could also be of Christian significance. It depicts, in the foreground, two notaries seated before large books with styluses in hand and an orator on a podium, and in the background, against a draped backdrop, a group of listeners expressing admiration for the speaker’s words. This may have been a meeting place for theological discussions (H. Marrou, St Augustin et la fin du monde antique, Paris 1939, p. 404, with ancient texts cited) or a catechumen school. From the most recent excavations comes a toga-clad statue from the early 5th century, which has been variously identified as C. Aurelius Symmachus, the famous praefectus annonae and prominent Ostian landowner (R. Calza, in Bull. Com., 1941, p. 113 ff.), or as his staunch religious opponent, Ragonius Vincentius Celsus, a figure well known in Ostia and Porto (G. Becatti, op. cit., p. 216; R. Calza, Museo ostiense, cit., p. 13, no. 55).
Ostia also boasts objects of minor arts, such as lamps with Christian symbols, mostly locally made by a certain Annio Ser... (G. B. De Rossi, in Bull. arch. crist., 2ª ser., 1 [1870], p. 80 ff.), lead frames for small mirrors, bronze rings, or glass pieces bearing clear allusions to Christian symbols. In addition to these predominantly Christian finds, there are a few Jewish relics. Among the latter is a large fragmentary inscription discovered in 1905 near Castelporziano, attesting to the presence of a significant Jewish community (*gerusia*) in the territory of Ostia (E. Ghislanzoni, in Notizie degli scavi, 1906, p. 115 ff.), and a tomb found in the cemetery of Porta Laurentina in 1936, which may have belonged to a Jew, judging by the name “M. Baenit,” similar to one mentioned in the Corpus Inscriptionum Judaicarum, Vatican City 1936, 671 (G. Calza, in Notizie degli Scavi, 1938, pp. 36, 38). — See pl. XXX. Raises Calza