The castles were originally built as Thessaloniki’s fortifications in earlier periods where they were of an absolute necessity for the protection of the city. The Acropolis was built on the highest location of the castles, and on the north-east peak of the Acropolis the Heptapyrgion was built to form the city’s last fort. The Heptapyrgion (also known as Genti-Koule) was used as a prison until 1989. Tourists can visit the Heptapyrgion, along with the Trigonio Tower in the entrance of the Acropolis only for some days a year. In the district many scenic alleys and small traditional taverns are to be found, while visitors can enjoy a splendid panoramic view of the entire city.

The White Tower is a round fort near the center of Thessaloniki city, which has become equivalent to the City’s Symbol. It was built in the 15th century as part of the city’s sea fortification. During the Ottoman Empire’s Occupation, the White Tower became a synonym for terrorism, due to the bloody executions which took place there. After the city’s liberation the Tower was whitewashed, so as to purify it from the blood that was shed in it. Nowadays, the internal part of the White Tower houses an exposition of the history of Thessaloniki.

Agios Dimitrios constitutes one of the most significant Christian monuments and the largest Greek Church. It was built on the remains of where the Roman Baths once stood in honor of Saint Dimitrios, the patron Saint of Thessaloniki. It was completely destroyed in the great fire of 1917 and rebuilt in 1948. The Crypt on the east end of the church, where Saint Dimitrios was tortured and killed by Roman soldiers, is currently a place of worship.

The Rotonda is a circular building originally built in 306 CE as a Pantheon or a Mausoleum for Galerius. Due to the fact that it wasn’t used at all in the Byzantine times, during the sovereignty of Theodosius the Great, the Rotonda was converted into a Christian Church of Saint Georgios, whereas it was converted into a mosque during the Ottoman Empire’s Occupation. Don’t forget to admire the unique in their kind mosaics of the 4th century CE. The iconography dates back to early 5th century, yet currently the surviving iconography are only that under the church’s dome.

The Triumphal Arch of Galerius, also known as “Kamara”, is one of the most characteristic monuments of Thessaloniki. It constitutes one of the most popular meeting points of both the residents and the visitors of Thessaloniki. It was built in 305 CE to celebrate the triumph of Galerius over the Persians. Only three pillars and one part of the upper stone construction have survived the original arch. The two main pillars are covered by marble sculptural panels. The original monument comprised four main pillars and two smaller ones on both sides, supporting the central construction.