Salona grew in the area of the Greek cities of Tragurium and Epetium on the river Jadro in the 3rd century BC.

Martia Iulia Valeria Salona Felix (the full name of the ancient city) was founded probably after the Roman civil wars under Julius Caesar.

The early Roman city encompassed the area around the Forum and Theatre, with an entrance, the Porta Caesarea, on the north-east side.

The city quickly acquired Roman characteristics: walls, a forum, a theatre, an amphitheatre which are the most conspicuous above-ground remains today, public baths, and an aqueduct.

[9][10][11][12] When the Roman Emperor Diocletian retired, he erected a monumental villa (palace) in a suburban location (6 km away).

[19] The connections were not only about exchange of goods and monuments, prominent individuals also traveled, remained to live and die at Salona (especially from Syria).

[19] Seemingly it was a big port as for the Battle of Sena Gallica (551), Byzantine general Jon sailed from it with 38 ships (compared to Ravenna's 12).

[20] Initially believed that grew to over 60,000 inhabitants, recent excavations found it was for one third larger than originally thought by the archaeologists.

[22] Pope Gregory I in July 600 wrote to the archbishop of Salona, Maximus, in which he expresses concern about the arrival of the Slavs ("de Sclavorum gente quae vobis valde imminet et affligor vehementer et conturbor").

[20] Refugees from Salona settled in other coastal and island cities (Decatera, Ragusa, Spalato, Tetrangourin, Diadora, Arbe, Vekla and Opara) and inside Diocletian's Palace.

[2] During the reign of Emperor Marcus Aurelius around 170 A.D., under the constant threat of Germanic tribes, the east and west suburbs were included in the walls, which were fortified with at least 90 towers.

The total circumference of the elliptical shape of the walls was approximately 4 km (2.5 mi), with varying width from enclosing 240 acres 1.9 to 2.5 meters (6.2 to 8.2 ft).

[2] Furthermore, in the first half of the sixth century, triangular-shaped endings were added to some square-shaped towers to improve the city's security and defense system.

There was an adjoining elongated spacious room to the north, housing a semicircular pool, the piscina, filled with cold water, the frigidarium.

After eastern and western expansion had occurred, the gate lost its primary purpose and became carrying construction of the aqueduct.

According to Kähler's reconstruction, the gate had two floors, of which the top one was very elaborately decorated with half columns, composite capitals, and window openings.

Several mosaics depicting mythological figures such as Apollo Orpheus and Triton have been transferred to the archaeological museum in Split.

It was built in the middle of the fourth century above the graves of four Praetorian guards who were executed in the arena during Diocletian's persecution of Christians.

[2] At the westernmost point of Salona, in the second half of the second century A.D., under the influence of Flavian architectural style, a monumental building was erected.

The presence of a Roman amphitheater indicates that gladiator fights were held in the city of Salona until the fifth century, when they were finally banned.

Through poles attached to the outer shell of the building, the whole arena could be covered with canvas, giving protection from the sun and rain.

There was a state box for the Province governor on the south side and opposite it seats of honor for the city magistrates.

On the south side of the amphitheater, beneath the auditorium, there were two vaulted rooms where gladiators worshipped Nemesis, the goddess of revenge and destiny.

[2] Gradina means a medieval hill fort built on the east walls by the Turks after capturing Klis.