The ruins of the ancient city of Salona, situated at the foot of the mountains just northeast of Split, are the most archaeologically important in Croatia. Start by paying your admission fee at Tusculum, near the northern entrance to the reserve. Built in 1898 by the site's ground-breaking archaeologist Monsignor Frane Bulić as a base for his research, it has a Roman-style drawing room with displays on the early archaeology undertaken here.
Salona was first mentioned as an Illyrian town in 119 BC and it's thought that it already had walls by then. The Romans seized the site in 78 BC and under the rule of Augustus it became the administrative headquarters of the empire's Dalmatian province. When Emperor Diocletian built his palace in Split at the end of the 3rd century AD, it was the proximity to Salona that attracted him. That grand history all came to a crashing halt in the 7th century, when the city was levelled by the invading Avars and then the Slavs. The inhabitants fled to take refuge within Diocletian's old palace walls and on the neighbouring islands, leaving Salona to decay.
While many of Salona's ancient treasures are now on display in Split's Archaeological Museum, there's a surprising amount in situ. Numerous sarcophagi are scattered about the area known as Manastirine, between the car park and the museum. This was a burial place for Christian martyrs prior to the decriminalisation of Christianity and includes the substantial remains of an early basilica.
From Tusculum, a path bordered by cypresses runs south to the northern city wall. From here you can get an overview of the foundations of buildings that compose the Episcopal Centre, including a three-aisled 5th-century cathedral with an octagonal baptistery, and the remains of Bishop Honorius’ basilica, with a ground plan in the form of a Greek cross. The ruins of public baths sit just across the narrow lane at the rear of the basilica.
Just beyond this complex and slightly to the right is the monumental 1st-century eastern city gate, Porta Caesarea, later engulfed by the city as it spread eastward. Grooves in the stone road left by ancient wheels can still be seen here, along with the remains of a covered aqueduct that ran along the top of the wall. It was probably built around the 1st century AD and supplied both Salona and Diocletian’s Palace with water from the Jadro River.
The original city spread west from here to the huge 2nd-century amphitheatre, destroyed in the 17th century by the Venetians to prevent it from being used as a refuge by Turkish raiders. At one time it could accommodate 18,000 spectators, which gives an idea of the size and importance of ancient Salona.
The main path leading to the amphitheatre follows the line of the ancient wall. Just to the right of the path (ie outside the wall) you'll pass another early Christian cemetery, where the remains of some of those killed in the amphitheatre were once buried, along with the ruins of the Five Martyrs Basilica, built in their honour.
Further ruins can be found among the vineyards and orchards to the left of the path, including the scant remains of the Forum and, nearby, a theatre and a Temple of Dionysus.
Salona is easily accessible on Split city bus 1 (single/return 13/22KN), which goes all the way to the parking lot every half-hour, departing from Trg Gaje Bulata.