Diagram by Greece Trips. Free to reuse with credit - CC BY 4.0.
It is part of the UNESCO-listed group of the city’s Palaeochristian and Byzantine monuments.
What survived, and what was rebuilt
The basilica burned in the great fire of 1917 and was rebuilt over the following decades, reusing what stood. So the building you walk into is a reconstruction of an early Christian five-aisled basilica, with original columns and capitals among it.
The pieces that matter most are the mosaics that survived the fire, panels showing the saint with donors and children, on the piers flanking the sanctuary. They are early, they are subtle, and they are why art historians come.
The crypt
Below the church is a crypt, opened in the twentieth century, built around what is identified in tradition as the site of the saint’s martyrdom, with Roman bath structures incorporated into it. It holds sculpture and architectural fragments and is cool, dim and quiet.
It usually keeps its own opening hours, separate from the church, which catches visitors out.
Visiting
It is a working church with services, and a major one. Modest dress, quiet, and no photography where it is asked. Allow thirty to forty-five minutes including the crypt.
The church sits a short walk uphill from Aristotelous Square and near the Roman forum, so it slots into the walk between the centre and the upper town.
Last checked August 2026. Service times and crypt hours change - see our editorial policy.
Common questions
Who is Agios Dimitrios?
Saint Demetrius, the patron saint of Thessaloniki, to whom the basilica is dedicated and on whose associated martyrdom site it stands.
Was Agios Dimitrios destroyed in the fire?
It burned in the great fire of 1917 and was rebuilt over the following decades, with original columns and some mosaics surviving.
What are the mosaics at Agios Dimitrios?
Early panels on the piers by the sanctuary showing the saint with donors and children, among the most important surviving early Christian mosaics in Greece.
Can you visit the crypt?
Yes, and it usually keeps separate opening hours from the church itself, so check before assuming both are open.
How long does a visit take?
Thirty to forty-five minutes including the crypt.
Next
Read things to do in Thessaloniki, the Rotunda, or Ano Poli.