On the north shore of the Aegean, Thessaloniki is a port city at the south end of the Axios River valley. It had been a regional capital of the late Roman Empire under the Emperor Galerius, who built a triumphal arch and palace there, including his rotunda mausoleum. Not much later, an early church was constructed above a Roman bath, replaced in the 7th century by a much larger five-aisled Basilica of St Demetrios with mosaics. The only city in Europe with a Jewish majority, it remained under Ottoman rule until it was occupied by the Greek army led by Prince Constantine in November 1912, at once becoming the second largest city in Greece. Refugees from the first two Balkan Wars then began descending on the city. Its great harbour had served as the main outlet for trade from the Balkans and was desired by all the newly independent Balkan countries adjacent to it
While Greece was still technically neutral, French and British forces occupied Salonika in 1915 to counter the Bulgarians nearby, bringing tens of thousands of soldiers from the British and French Empires to the region. Then in 1917 a devastating fire destroyed most of the old city, leaving 70,000 homeless. Immediately the Greek government in Athens began planning to exploit the opportunity to redesign and rebuild the city with broad straight avenues and no ethnically separate quarters. Finally, after the Greek debacle in Asia Minor in September 1922, a much greater human flood inundated the area, doubling the city’s population within weeks.
Although the mosaics in the Basilica were lost in the fire, excavations in the crypt underneath revealed the discovery of a Roman bath, reused as an early church with an empty tomb. Gilbert Bagnani and the other Italian students had heard a lecture by the excavator and would have been most interested to see the newly exposed evidence for a Roman bath and sacred spring. This was long considered a source of holy water associated with the martyrdom and burial site of St Demetrios beneath the Basilica, and so once a place of pilgrimage.
So, when Gilbert visited Salonika in May 1923, it was a city in transition from Eastern and Jewish dominated by Turks to Western and Orthodox. In the following year, all the remaining Moslems would be ordered to leave, taking their belongings with them, to provide space for the homeless Anatolian refugees, many speaking Turkish.
“On Wednesday  got to Salonika which we visited pretty thoroughly. It is a most depressing town & frightfully dirty but the churches are most interesting only they have been filled with refugees. Some of the mosaics are wonderful & it is nice of them not to have knocked down the minarets.” (Friday, 18 May 1923)