It enjoyed the privilege of bearing the full name of its founder, who entrusted its deductio, like many other tasks of the Empire, to his general and close friend Marcus Vipsanius Agrippa.

Veteran soldiers of the legions IV Macedonica, VI Victrix and X Gemina, discharged after the hard campaign against the Asturians and Cantabrians, participated in the foundation of the city, with the double intention of guaranteeing the defense of the territory at the same time as establishing the presence of Rome in it.

Caesaraugusta assumed from the beginning the role of regional head, replacing the colony Victrix Ivlia Celsa (in the current Velilla de Ebro).

The period of the city's greatest apogee in the first and second centuries brought many of the great public works, some of which can still be seen today: the forum, the river port, which made Caesaraugusta the main redistributor of goods in the Ebro valley, the public baths, the theater or the city's first bridge, located on the site of the current Stone Bridge and which was probably a work of ashlar or a mixture of stone and wood.

According to the remains of the first and second centuries found outside the perimeter of the preserved walls (Plaza de la Magdalena, Antonio Agustín, Rebolería, Añón and Teniente Coronel Valenzuela streets, to cite a few examples), the initial extension of the city would occupy the current neighborhood of Magdalena and Tenerías to the east until the course of the Huerva river, and to the south a strip of land that would reach Cinco de Marzo and San Miguel streets, parallel to the Coso Alto.

The forum of the Augustan or Saluitan period (located in the current Plaza de la Seo and the museum of the river port) had a mercantile character linked to the transport of goods to and from Tortosa across the Ebro, and was very possibly in operation before the Roman colonial foundation.

The conventus Caesaraugustanus was one of the largest and included Pamplona and Irún to the north, Calahorra to the west, Alcalá de Henares to the south and Lérida to the east.

In addition, it had a religious capital, with its own cult, since it had a Genius conventus caesaraugustani with its own priesthood and received tributes and sacred offerings from all the cities of the administrative demarcation.

The most outstanding work in the time of Tiberius (14 A.D. - 37) was the remodeling of the forum, which was enlarged by designing a large rectangle of more than 50 meters on the western side, which housed tents built with ashlar masonry and provided with a basement.

According to another theory of the location of the cardo, it could start from this forum and not need the setback that would lead to the door Cinegia from the street of Don Jaime I (also called San Gil), depending on the hypothesis and planimetry proposed by Maria Pilar Galve in 2004.

Numerous examples of domus (or single-family houses) of wealthy citizens of the city had private baths, although other public thermal establishments have also appeared, such as those in the Plaza de Santa Marta, which preserved the remains of paintings of garlands and flowers.

In the 3rd century the theater of Caesaraugusta is modified again, which may indicate a new function for the space of this building, where perhaps the theatrical spectacle itself is no longer preeminent, in favor of the celebration of other types of entertainment.

In them, polychrome mosaic pavements of great proportions can be found, such as that of the House of Orpheus, a domus of big proportions whose hall had a surface area of 47 m2; or that of the Triumph of Bacchus that appeared next to an important sculptural group: the Ena Group (two nymphs performing music, reflecting exquisite taste, delicate chiseling and a philhellenistic taste introduced in the Empire under the Antonines), preserved in the Marés museum in Barcelona; previous dating, however, it was attributed these mosaics and sculptures to the 2nd century.

There is also a proliferation of agrarian villas in the process of ruralization experienced by Roman culture in its final period, and the great differences that begin to appear between honestiores (or wealthy) and humiliores (of humble social status) citizens.

After reaching power, Diocletian (284-305) reformed the State and the Roman political system, which had suffered a prolonged crisis that threatened the unity of the Empire since the time of Marcus Aurelius (161-180), facilitating the barbarian incursions.

[8] In the absence of direct information, it is to suppose that the city continued being demilitarized, falling the defense of the walls in case of attack on the local militia and especially on the collegia iuvenum, a body formed by the sons of the upper classes.

The peasants close to the city took refuge inside the walls; those farther away had to rely on small troops stationed in watchtowers regularly distributed along the roads for their defense.

[9] Within the administrative reforms initiated by Diocletian, the Hispania Citerior was divided in three: Gallaecia, Tarraconensis and Carthaginensis, with praeses perfectissimus, all part of the Diocesis Hispaniarum, with capital in Merida.

[11] Archaeology shows the existence of large luxurious houses, an import of exclusive products from Rome and the south of France and an active trade with North Africa.

[12] The main source of the 4th century, Paulinus of Nola, whose wife Therasia had possessions in Zaragoza, Tarragona and Barcelona, recounts that he himself dwells in Caesaraugusta, among other localities, and praises its extensive territory and its walls.

[11] Taking the North African city of Timgad as a model, it is possible to reconstruct approximately the local government: curia or senate, magistrates and populus.

There were approximately one hundred curiales, of whom a minority were honorati exempt from munera, tax burdens, classified in descending order into clarissimi, of senatorial rank, the perfectissimi, from 326 different from the equites, and the sacerdotales, former priests.

Among the services rendered to the city, apart from the payment of the summa honoraria upon taking office, the officials had to organize games, maintain the public baths, supervise the bringing and evacuation of water, officially represent the city, control and supervise the conservation and construction of roads, bridges, aqueducts, public buildings and walls, and oversee the prices of the market, among other activities.

The functions of the curator were to oversee the financial management, the registration of the acta, the execution of public works, the provisioning, the control of prices, in charge of the police and the instruction of some minor matters; the duouiri, the other magistrates, aediles and quaestors, were subordinate to them.

In it he speaks of the Innumerable Martyrs, in reality 18 —Optatus, Lupercus, Suceso, Martial, Urbanus, Quintilianus, Julia, Publius, Fronton, Felix, Caecilian, Eventius, Primitivus, Apodemus and four Saturnines—, besides Engratia, Valerius and Vincent and Gaius and Clement, the latter confessors who were not killed.

Valerius, who still attended the council of Iliberis around 306,[15] belonged to the domus infulata of the Valerians, a dynasty of Ceasaraugustan bishops named Valero/Valerius, which shows that Saragossa was already an episcopal see from the middle of the 3rd century.

[16] There are indications that Saint Engracia and the martyrs would have been buried in a small building dedicated to their cult, a Martyrium, to which a mosaic of the 4th century with Christian symbolism preserved in the Museum of Saragossa could belong.

[19] The second sarcophagus, usually called the Petrine trilogy, shows the miracle of the fountain, the arrest of Peter, the scene of the rooster, the healing of the blind man, the conversion of water into wine, the multiplication of the loaves and fishes and the resurrection of Lazarus.

[24] The internal crisis of the Empire was compounded by the fact that in the winter of 405-406 the Rhine froze and the Germanic peoples crossed the river on foot: the Suebi, Vandals and Alans set out to conquer and plunder the lands of Gaul.

The colonial, in its most representative parts, must have been completed at the end of the 1st century, being one of the fundamental elements of the rank and prestige of Caesar Augusta.However, in 2003, an important work of the whole of what was known so far of the wall [... ], allowed to assure its authors that the wall was possibly built in the second half of the 3rd century and that the execution technique was uniform: inner body of opus cæmenticium with outer covering of ashlar and thickness of 7 m; while the eastern side would be of ashlar with 6 m of thickness.