The Rotunda is the massive round brick building just north of Egnatia Street in Thessaloniki, a few steps up from the Arch of Galerius. Built by the Roman emperor Galerius in the early 4th century, it has been a Roman monument, a church, a mosque and a museum, and it still has the minaret to prove it. Inside, under one of the widest ancient domes to survive, are some of the earliest Christian mosaics in the eastern Mediterranean.
The Rotunda at a glance
- Where: Agios Georgios Square (Plateia Agiou Georgiou), at the top of Dimitriou Gounari Street, about a minute's walk uphill from the Arch of Galerius.
- Built: around 306 AD, as part of Galerius's palace quarter.
- What it is today: a monument run by the archaeological service and a church of St George, with a liturgy about once a month and occasional concerts. It is part of the UNESCO World Heritage Site of Paleochristian and Byzantine Monuments of Thessaloniki, listed in 1988.
- Size: about 24.5 metres across inside and almost 30 metres high, with walls more than 6 metres thick.
- Time needed: 30–45 minutes, longer if you want to study the mosaics.
From emperor's monument to church, mosque and back
Galerius ruled the eastern part of the Roman Empire and made Thessaloniki one of his capitals. The Rotunda stood at the end of a ceremonial street that ran from his palace, past the triumphal arch, up to this round building. Nobody knows for sure what it was for: a temple and an imperial mausoleum are the main theories. Galerius died in 311 and was buried elsewhere, in present-day Serbia, so it never served as his tomb. Before the end of the 4th century, or in the 5th, it was turned into a church: an apse was added on the east side, the interior was lined with mosaics, and it was dedicated to the Archangels.
Under Ottoman rule the church became a mosque around 1590, and a minaret was built beside it. After Thessaloniki became part of Greece in 1912 it was consecrated as a church again, and in the following decades it served for a time as a museum. The name Agios Georgios (St George) comes from a small church that stood next to it. The earthquake of 1978 damaged the building, which then spent decades under scaffolding; after a full restoration it reopened to visitors at the end of 2015.
What to look for
- The dome mosaics: in the lowest band of the dome, eight panels show pairs of praying men in white robes against golden architecture with arches, peacocks and jewelled columns. Inscriptions next to them give their names and a month, probably their feast day.
- The vaults over the recesses: the arched niches around the walls still have gold and silver mosaic with geometric patterns, birds, fruit and baskets.
- The walls: more than 6 metres of Roman brick and stone. Look up into the eight deep recesses that cut through them.
- The minaret: the slender Ottoman tower next to the building survives from its centuries as a mosque.
- The courtyard: walk round the outside to see the apse added for the church and the stones and architectural pieces displayed in the grounds.
A dome full of lost saints
When the mosaics were complete they covered well over a thousand square metres, rising from the saints in the lower band through a lost middle ring to a figure of Christ at the top of the dome. Most of it has gone: in the middle zone only feet and the hems of robes survive, and of the centre only fragments of angels, a rainbow border and stars. Experts still argue about the date, with suggestions ranging from the late 4th to the 6th century, and about whether the praying men are martyrs or donors.
Tips for your visit
- Go in the morning or late afternoon, when the low sun lights the gold mosaics through the windows and the interior is quieter.
- Bring binoculars or use your phone's zoom: the best mosaics are high up in the dome.
- Dress as you would for a church and keep your voice down, especially if a service or event is being prepared.
Nearby
- Arch of Galerius (Kamara): the triumphal arch on Egnatia Street with marble reliefs of Galerius's war against the Persians, about a minute's walk downhill.
- Palace of Galerius: the excavated remains of the emperor's palace around Navarinou Square, a few minutes' walk south.
- Hagia Sophia: the 8th-century church with a domed mosaic of the Ascension, a short walk west along Egnatia Street.
- Church of Agios Dimitrios: the basilica of the city's patron saint, with his crypt and early mosaics, further west in the upper part of the centre.
See Thessaloniki with World City Trail
Our Thessaloniki scavenger hunt turns the city centre into a game you play on your phone. The route links 10 stops and takes around 2 hours, with about 53 minutes of walking. The Rotunda is one of the stops, along with the Church of Agios Dimitrios. You can play in English, German, French, Italian or Greek.
If you prefer a different format, there is also a self-guided walking tour and an outdoor escape game in Thessaloniki.
Play the Thessaloniki scavenger hunt →
Take the self-guided walking tour of Thessaloniki →
Play the outdoor escape game in Thessaloniki →
Facts checked in October 2026.