Question: What distinction does the city where Heptapyrgion is located have in regards to size in Greece?

full_context: Document 1: Economy of Greece: In recent years a number of well-known tourism-related organizations have placed Greek destinations in the top of their lists. In 2009 Lonely Planet ranked Thessaloniki, the country's second-largest city, the world's fifth best "Ultimate Party Town", alongside cities such as Montreal and Dubai, while in 2011 the island of Santorini was voted as the best island in the world by Travel + Leisure. The neighbouring island of Mykonos was ranked as the 5th best island Europe. Thessaloniki was the European Youth Capital in 2014.
Document 2: Chlemoutsi: It was built in the early 1220s by the Crusader rulers of the Principality of Achaea as their main stronghold, and is perhaps the finest fortification of the early period of Frankish rule in Greece preserved in the country today. The castle is located on a small plateau above sea level, and comprises a central hexagonal keep, built around an inner courtyard and containing two-storeyed halls along its entire length, and complemented by an outer wall enclosing an outer yard on its western side. The castle is largely preserved in its original 13th-century state, with only minor later modifications for the installation of artillery.
Document 3: Greece: Greece is a developed country with high standards of living[citation needed] and high Human Development Index. Its economy mainly comprises the service sector (85.0%) and industry (12.0%), while agriculture makes up 3.0% of the national economic output. Important Greek industries include tourism (with 14.9 million international tourists in 2009, it is ranked as the 7th most visited country in the European Union and 16th in the world by the United Nations World Tourism Organization) and merchant shipping (at 16.2% of the world's total capacity, the Greek merchant marine is the largest in the world), while the country is also a considerable agricultural producer (including fisheries) within the union.
Document 4: Selimiye Barracks: Selimiye Barracks (Turkish: Selimiye Kışlası), also known as Scutari Barracks, is a Turkish Army barracks located in the Üsküdar district on the Asian part of Istanbul, Turkey. It was built first in 1800 by Sultan Selim III for the soldiers of the newly established  Nizam-ı Cedid (literally "New Order") in frame of the Ottoman military reform efforts.
Document 5: Peqin Castle: The Peqin Castle () is a castle in Peqin, Albania. In the Roman times the city was known by the name of Clodiana, an Illyrian-inhabited territory. The foundations of the castle are thought to date from the Roman period, the time of the construction of the Via Egnatia. Its walls at one point had a height of around . The castle was later rebuilt and expanded during the Turkish occupation of Albania, at which time it was passed into the control of the Sipahi (lord) of the local fief, who added a palace and a harem. The last resident of the castle was Demir Pasha.
Document 6: Hagia Sophia: Hagia Sophia (/ ˈhɑːɡiə soʊˈfiːə /; from the Greek: Αγία Σοφία, pronounced (aˈʝia soˈfia), ``Holy Wisdom ''; Latin: Sancta Sophia or Sancta Sapientia; Turkish: Ayasofya) was a Greek Orthodox Christian patriarchal basilica (church), later an imperial mosque, and is now a museum (Ayasofya Müzesi) in Istanbul, Turkey. From the date of its construction in 537 AD, and until 1453, it served as an Eastern Orthodox cathedral and seat of the Patriarch of Constantinople, except between 1204 and 1261, when it was converted by the Fourth Crusaders to a Roman Catholic cathedral under the Latin Empire. The building was later converted into an Ottoman mosque from 29 May 1453 until 1931. It was then secularized and opened as a museum on 1 February 1935. Famous in particular for its massive dome, it is considered the epitome of Byzantine architecture and is said to have`` changed the history of architecture''. It remained the world's largest cathedral for nearly a thousand years, until Seville Cathedral was completed in 1520.
Document 7: Economy of Greece: Greece is a developed country with an economy based on the service (82.8%) and industrial sectors (13.3%). The agricultural sector contributed 3.9% of national economic output in 2015. Important Greek industries include tourism and shipping. With 18 million international tourists in 2013, Greece was the 7th most visited country in the European Union and 16th in the world. The Greek Merchant Navy is the largest in the world, with Greek-owned vessels accounting for 15% of global deadweight tonnage as of 2013. The increased demand for international maritime transportation between Greece and Asia has resulted in unprecedented investment in the shipping industry.
Document 8: Economy of Greece: Between 2005 and 2011, Greece has had the highest percentage increase in industrial output compared to 2005 levels out of all European Union members, with an increase of 6%. Eurostat statistics show that the industrial sector was hit by the Greek financial crisis throughout 2009 and 2010, with domestic output decreasing by 5.8% and industrial production in general by 13.4%. Currently, Greece is ranked third in the European Union in the production of marble (over 920,000 tons), after Italy and Spain.
Document 9: Greece: Internet cafés that provide net access, office applications and multiplayer gaming are also a common sight in the country, while mobile internet on 3G and 4G- LTE cellphone networks and Wi-Fi connections can be found almost everywhere. 3G/4G mobile internet usage has been on a sharp increase in recent years, with a 340% increase between August 2011 and August 2012. The United Nations International Telecommunication Union ranks Greece among the top 30 countries with a highly developed information and communications infrastructure.
Document 10: Greece: Greece is a democratic and developed country with an advanced high-income economy, a high quality of life and a very high standard of living. A founding member of the United Nations, Greece was the tenth member to join the European Communities (precursor to the European Union) and has been part of the Eurozone since 2001. It is also a member of numerous other international institutions, including the Council of Europe, NATO,[a] OECD, OIF, OSCE and the WTO. Greece, which is one of the world's largest shipping powers, middle powers and top tourist destinations, has the largest economy in the Balkans, where it is an important regional investor.
Document 11: Greece: The vast majority of visitors in Greece in 2007 came from the European continent, numbering 12.7 million, while the most visitors from a single nationality were those from the United Kingdom, (2.6 million), followed closely by those from Germany (2.3 million). In 2010, the most visited region of Greece was that of Central Macedonia, with 18% of the country's total tourist flow (amounting to 3.6 million tourists), followed by Attica with 2.6 million and the Peloponnese with 1.8 million. Northern Greece is the country's most-visited geographical region, with 6.5 million tourists, while Central Greece is second with 6.3 million.
Document 12: Institute of technology: In Turkey and the Ottoman Empire, the oldest technical university is Istanbul Technical University. Its graduates contributed to a wide variety of activities in scientific research and development. In 1950s, 2 technical universities were opened in Ankara and Trabzon. In recent years, Yildiz University is reorganized as Yildiz Technical University and 2 institutes of technology were founded in Kocaeli and Izmir. In 2010, another technical university named Bursa Technical University was founded in Bursa. Moreover, a sixth technical university is about to be opened in Konya named Konya Technical University.
Document 13: Heptapyrgion (Thessaloniki): The Heptapyrgion (), modern Eptapyrgio (Επταπύργιο), also popularly known by its Ottoman Turkish name Yedi Kule (Γεντί Κουλέ), is a Byzantine and Ottoman-era fortress situated on the north-eastern corner of the Acropolis of Thessaloniki in Greece. Despite its name, which in both languages means "Fortress of Seven Towers", it features ten, and was probably named after the Yedikule Fortress in Constantinople (modern Istanbul, Turkey). It served as the major redoubt of the city's acropolis, as well as the seat of its garrison commander in Ottoman times, until the late 19th century. It was then converted to a prison (Φυλακές Επταπυργίου), which remained open until 1989. References to the infamous Yedi Kule prison abound in the Greek "rebetika" songs. Restoration and archaeological work began in the 1970s and continues to this day.
Document 14: Economy of Greece: According to Eurostat, Greece's largest port by tons of goods transported in 2010 is the port of Aghioi Theodoroi, with 17.38 million tons. The Port of Thessaloniki comes second with 15.8 million tons, followed by the Port of Piraeus, with 13.2 million tons, and the port of Eleusis, with 12.37 million tons. The total number of goods transported through Greece in 2010 amounted to 124.38 million tons, a considerable drop from the 164.3 million tons transported through the country in 2007. Since then, Piraeus has grown to become the Mediterranean's third-largest port thanks to heavy investment by Chinese logistics giant COSCO. In 2013, Piraeus was declared the fastest-growing port in the world.
Document 15: Sultan Ahmed Mosque: The Sultan Ahmed Mosque or Sultan Ahmet Mosque (Turkish: Sultan Ahmet Camii) is a historic mosque located in Istanbul, Turkey. A popular tourist site, the Sultan Ahmed Mosque continues to function as a mosque today; men still kneel in prayer on the mosque's lush red carpet after the call to prayer. The Blue Mosque, as it is popularly known, was constructed between 1609 and 1616 during the rule of Ahmed I. Its Külliye contains Ahmed's tomb, a madrasah and a hospice. Hand - painted blue tiles adorn the mosque's interior walls, and at night the mosque is bathed in blue as lights frame the mosque's five main domes, six minarets and eight secondary domes. It sits next to the Hagia Sophia, another popular tourist site.
ground_truth: the country's second-largest city
sub_queries: Heptapyrgion >> location Answer: Thessaloniki
What distinction does the city of Thessaloniki have in regards to size in Greece? Answer: the country's second-largest city