UNESCO Sites in Croatia: The Diocletian’s Palace in Split

Sergio Andrea Posenato
8 min readJun 21, 2024

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  • The Residential Palace of the Roman Emperor Diocletian (295–305 AD) transformed and was incorporated in the city center of Split
  • It is one of the finest Late Antiquity construction therefore included since 1979 in UNESCO’s World Heritage List
  • Diocletian was the first Roman Emperor that in 305 AD had been in retirement in his Palace in Split

In the Dalmatian coast is located the historical and economically important city of Split. Situated on the Dalmatian coast, it is a major touristic resort, an harbour and home of one of the most passionate football supporters in Europe, the Hajduk Split. It is also the house of a masterpiece of Late Antiquity construction and amazingly incorporated in the city center, which is the Diocletian’s Palace. The Palace was a fortified and deluxe house for the retirement of the Emperor Diocletian and was builded in about ten years (295–305 AD, meaning Anno Domini after the birth of Jesus). Diocletian, indeed, was borned nearby Split in the ancient city of Salonae in 245 AD and was Emperor between 284 and 305 AD. Was a famous Roman Emperor for three main politics: he reformed the Empire establishing the Tetrarchy (dividing the Empire in four chiefs, two Augusti and two Caesars) as a response to the rise of Empire in the 3th century, he unfortunately pursued the last major persecution of Christians and all in all, was the first Emperor that went in retirement. He retired indeed in his Palace in Split afterwards was incorporated in the city center of Split during the Middle Ages. The palace had also later addition, which makes it a 1700 years old historic and artistic unique urban facility included since 1979 in UNESCO’s World Heritage List.

The structure of Diocletian’s Palace

The deluxe and imperial residence has a rectangular form and has an extension of 30000 m2. The walls are 215 m long in the east and west side, 175 m long in the north walls and 180 m long in the south part of the palace. The fortified and luxurious palace has in the beginning sixteen towers spreaded in the four walls and four doors. Inside the palace, the northern part was dedicated to lodge military staff and service while the southern part was addressed to accommodate the Emperor´s residence and for religious aims.

Viel of Split with the southern walls of the Diocletian´s Palace incorpored now in the city center, Author: Falk2, Wikimedia Commons

Adding some more information about the Emperor Diocletian, as previously said, he was born nearby Split in the former capital of the Roman province of Dalmatia, which was the city of Salona. He was declared emperor by the legions in 284 A.D. and he is mostly famous for the institution of the tetrarchy, which leaded the construction of new imperial residences for the two Augusti in the new divided empire (see my article here about one of the two Augusti,Galerius, with his Rotunda in Thessaloniki). Anyway, the Diocletian’s Palace is also peculiar, because it was built for the retirement of the emperor, who lived there between 305 until he died in 316.

During the centuries and throughout the early Middle Ages, architectural activities occurred and changed the Palace´s upper floor, especially at the beginning of the 7th century A.D. when the inhabitants of Salona, the capital of the Roman province of Dalmatia located just about 5 km north of Split, left their homes and escaped to Split due to the invasion of the Slavic tribes that entered in all the Balkans and broke the defences of the former Eastern Roman Empire. The Romans found indeed a defence inside the Diocletian’s Palace, that before was left uninhabited for about three centuries. They started indeed to live in wooded houses, beginning the urban evolution that led the creation of the actual city center of Split incorporated in the walls and with the remaining parts of the Palace.

Among the architectural buildings from the original Diocletian’s Palace that it is possible to see today on the upper floor and that I will illustrate later, also the basement halls of the southern part of the Palace are interesting. This part indeed shows the authentic floor design of the Emperor’s Palace and it is possible to see them in a Museum. The project aim of the base halls was to provide to the southern part the same ground level of the northern part in an inclined terrain that goes to the sea, as well as a strong basis for the Palace. Interesting is also to discover in the Museum´s of the basement halls, how the spaces were reused in the early Middle Ages, for example as shelter for the lower classes escaped from the nearby city of Salona or as water wells and even spaces for an olive oil/wine press.

The Diocletian´s Palace sites: Temple of Jupiter and Diocletian’s Mausoleum (Split’s Cathedral)

The combination between the Diocletian’s Palace and the construction of the city center of Split from the early Middle Ages creates a unique combination of architectures, from antiques to medieval ones. Among the many attractions to see while walking in the tiny roads of the city, I will focus here on two monuments from the Diocletian’s Palace that I mentioned in the paragraph’s title.

I start the list with the Baptistery (Temple of Jupiter) that was erected between 295 and 305 as a part of the Diocletian’s Palace. The temple was indeed committed to the Roman God and the favourite Diocletian´s God, Jupiter. After, it was converted into a baptistery in the 7th century. Throughout the main entrance of the Temple, ornaments of flowers and leaves are present, as well as images of a wide range of Roman gods and heroes (you can read the full list of Gods in the inside informative box). In front of the main entrance are the remains of a column on the right side of the door that once supported a portico, and a black sphinx on the right. The sphinx is made of granite and was already ancient when the Roman took it from Egypt in the 3th century, but it was unfortunately disfigured by the early christians in the 7th century, who considered it as a pagan image. Inside, the masterpiece of the Temple is the original barrel-like vault composed of 64 panels, every single vault with rich adorned sides and faces expressing a peculiar emotion in the center. Why the faces show a personal emotion on a temple ́s roof, it’s still a mystery, but it is possible that they took part in the religious ceremonies in the temple. In addition to the vault, the temple contains various things, such as the oldest image of a croatian king, sarcophagi from the early Middle Ages containing the remains of two Archbishops of Split and a renaissance one. All in all, a bronze statue of St.John the Baptist manufactured by a local architect.

The original barrel-like vault of the Temple of Jupiter, Foto taken by me

The second monument is the Diocletian’s Mausoleum (Cathedral of Split), which is one of the best preserved buildings of the fourth century and later converted from about the mid of seventh century into the actual Cathedral of Split. It was built as a chapel with an octagonal setup and the cylindrical interior is topped by a dome. Immediately inside the Mausoleum, the space is defined by the impressive Corinthian columns pushed against the wall and above them another line of smaller columns. The funeral service of the Mausoleum was assured by the internal relief representing portraits of the Emperor Diocletian, his wife, Roman´s Gods such as Hermes, Psyhopompos as well as other motifs. Architectural attention is also deserved by the cupola built in the fourth century, which also looking at it inside of Mausoleum has a simple but distinctive style.

The altar, two of the eight Corinthian columns, motifs and a small part of the cupola of the Diocletian’s Mausoleum (Cathedral of Split), photo taken by m

A pearl inside the Diocletian´s Palace western´s entrance: The Church of St.Martin

The combination between antique and medieval style is well expressed in a small unique place which is The Church of St. Martin. The little church is located in the western wall and impressively, exactly above the Gold Door of the Diocletian’s Palace.

The site was indeed a corridor (10 m X 1.64 m) that was used by the guards of the Palace. There’s indeed small windows on the south side that were used for monitoring the entrance in the Palace. These parts are authentic from the Palace and in addition, a window on the north side was placed in the Middle Ages and used for defence against the Turks.

The church is from the early Middle Ages and specifically from the ninth century. It is dedicated to St.Martin, who was the founder of the western monasticism and an appreciated figure in Frankish Kingdom as Bishop of Gaul.

Afterwards it was established together with the church the Monastery of the Dominican Sisters of the Third Order and the first mention of the monastery lies back in 1372. When an epidemic started in Split, both the nun and the population were affected with fatalities and due to this the nun needed to leave the monastery and go in isolation. This relocation led the Monastery to be abandoned, subjected to robbery and devastation. After some years anyway, the nun restored the Monastery but they left the little church as a storage box. The church stayed in this condition until 1890 when it was discovered by the archaeologist father France Bulic. The archaeologist recommended, after his research on the Diocletian’s Palace, to renovate the church and also a new altar and nave was added.

The architrave of church of St.Martin in the corridor of the Diocletian's Place Gold Door, foto taken by me

Conclusion

The city center of Split is really a fantastic merge of Roman late antiquity and Middle Ages architecture. Indeed, it’s remarkable that the city centre developed from the ruins of a Palace and incorporated it. The Mausoleum of the Emperor was transformed into the Cathedral of the city, while the walls of the Palace in the walls of the Split’s city center. In addition, there are plenty of places to discover and especially the sites which combine the two styles, antique and medieval, impressed me the most.

References

The Church of St.Martin, Sestre Dominikanke

The Substructures of Diocletian´s Palace, Split City Museum

Temple of Jupiter Museum

Diocletian’s Mausoleum Museum

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Sergio Andrea Posenato

I write about history, politics, philosophy and miscellaneous.