I only had half a day to visit the inscribed sites in Thessaloniki so I had to carefully plan my visit. First I picked the churches I wanted to visit most (7 out of 14) and planned a route which went through them. They are all not far from each other and the route can be perfectly done by foot. The problem is finding out the opening times. From the ones I wanted to visit (Rotunda, Acheiropoietos, Hagia Sophia, Panagia Chalkeon, Hagios Demetrios, Hosios David and Nikloaus Orfanos) only the Rotunda now serves as a museum. All the others are functioning churches and it is practically impossible to find out whether they are open to visitors or not before you head there unless you can call them before and talk to the priests in Greek. I was lucky though. In a summer Friday morning all the churches were open, although there were services taking place in three of them. Despite processes of secularisation, Greece is still a deeply religious country. Even morning masses in a working day proved to be well visited. It was impossible to visit the churches during service, but I could still stand at the door, listen to the liturgy and catch a glimpse of the interior, which is way better that standing in front of a closed church.

I will try to summarise my impressions:

1) The Rotunda surprised me as a very impressive massive Roman building. It was the second largest Roman building at the time after the Pantheon. Its walls are 5 meters thick and the ceiling still looks very high even to modern eyes. Many of the frescoes survived and I found Rotunda to be the most impressive of the churches for its size, form and time of construction. Nearby is the Galerius Palace which includes an underground visitor centre and Arch of Galerius. Both were initially planned as a part of the nomination, but were later omitted as the nomination shifted to focus only on the Byzantine heritage. Yet it is worthwhile to visit them as they provide some background as to what Roman Thessaloniki looked like when the Rotunda was built. The Rotunda was not planned as a church at all, but probably as a mausoleum for Galerius. It was, however, turned into a church soon after its completion.

2) Hagia Sophia is the largest of the inscribed churches. It has some nice frescoes, but many were destroyed in a fire in 1890. It surprised me to find out that the Ottomans renovated it (as a mosque), but without interfering too strongly with the original style of the church. They added some faux marble which fits the church in both colour and form.

3) Hagios Demetrios has a very nice prolonged nave, somewhat similar to Acheiropoietos. I couldn't pay any of the two the attention they deserved due to the masses being held there during my visit, but I still stepped in. The catacombs of Hagios Demeterios can be visited even during service. You need to be audacious enough to cross the entire church. In the back of the church you can descend and visit the museum downstairs, listening to the service from below. The museum features only Greek signs, but is still nice to visit.

4) Niklaus Orfanos has the nicest frescoes. It has never been destroyed or ceased to function as a church. It is covered by beautiful floor to ceiling frescoes. Similar to nearby Hosios David it is in the Ano Poli (Upper Town), with characteristic steep narrow streets and old Ottoman houses.

5) When I finished with the churches I went on to visit the Byzantine fortifications. I visited Trigonio, a watch tower. Nearby are numerous cafes with a view of the entire city and the sea. I then walked to Heptapyrgion, a complex that used to serve as a citadel and then as a prison. The outer layer still looks original and it is fun to walk around. It is now used to show some modern art exhibitions and I found them to disagree with the setting.

In general, Thessaloniki gives you a good impression of the history of Byzantine architecture. It has well preserved churches from each age during the history of Byzantium. The churches are also different enough to merit visiting several, or even all of them. The frescoes in most churches were a bit disappointing, but Nikolaus Orfanos was a good compensation in this respect.

I would additionally wholeheartedly recommend visiting the Archaeological Museum of Thessaloniki. It is well designed, with bilingual signs and all of the exhibits originate from Macedonia. Its collection of Macedonian gold objects is of world quality. It struck me how rich and technologically advanced the Greeks of the northern provinces were during antiquity, as they are by far less known than their southern counterparts of the Peloponnese.