The colony of Tomis was founded in the 7th century BC by the ancient Greeks. It prospered during the following centuries, and continued to thrive after the Roman conquest of the area in the first century BC. Tomis was famous as the exile place of Ovid, where the poet wrote his Tristia and Epistulae ex Ponto. Tomis was later renamed Constantiana in honour of Constantia, the half-sister of Emperor Constantine the Great, and was often besieged during the invasions of the migratory peoples that headed towards the Roman Empire in the late ancient period. It became part of the Bulgarian Empire, then the area was organised as an independent principality, to be conquered by the Hospodar of Wallachia in late 14th century. The entire province of Dobrudja (Dobrogea) was conquered by the Ottoman about 1416 and became part of the Ottoman Empire for about four centuries and a half.
The geographical position of Constanţa made it a constant victim in the Russian–Ottoman wars of the 18th and 19th centuries. In 1780, according to the information of a Polish agent (W. Czrzanowski), Constanţa was “one of the most important ports, where Greek and Turkish vessels call at”. Thus, although its harbour was completely ruined, several commercial ships belonging to Ottoman Greeks traded there . A quarter century later, by 1804, sources refer to ships carrying olives and olive oil to Constanţa, where the existence of a mercantile association was also mentioned . During the Russian–Ottoman war of 1806–1812 Constanţa was again damaged. In August 1809 a Cossack detachment led by General Plotov reached Constanţa, and the Ottoman military commander-in-chief surrendered the town with its fortifications, ammunitions and provisions in exchange for the permission to leave to Varna together with the 2,000 local inhabitants. The town was poorly fortified (with a wall and a ditch) and it was later looted and burnt down .
Constanţa was besieged once more in 1828, when Helmuth von Moltke depicted the town as “surrounded from three parts by the sea and steep, 100 feet high rocks, being is only accessible from the north […] This harbour has only seven feet of water and is completely exposed to the southerly winds”. Maritime trade was limited, as its harbour did not allow a safe traffic. Population amounted to about 2,000 people, and the Ottomans had fortified the town towards the mainland with three bulwarks . After its occupation, Constanţa was intensely used by the Russian fleet as a supply base for the land troops fighting in the Balkans .
By the early 1830s, sailing guides mentioned that ships could anchor in a certain area of the harbour, where the water was about 12–17 feet deep. They could also remain in the roadstead, where conditions were considered adequate. However, commercial exchanges were “almost inexistent”. The importance of the town grew with the development of the Danubian ports of Brăila and Galaţi, when the difficulties of navigation through the Sulina mouth of the river made interested commercial circles analyse the opportunity of building a canal or a railway between the Danube and the Black Sea. At the same time, in 1839, the Austrian Steam Navigation Company introduced a coach between Cernavodă and Constanţa, thus shortening with two days the journey from Vienna to Constantinople. The project for the construction of a canal or a railway was intensely debated during this period, with many engineers, economists, diplomats and journalists referring to its advantages or hindrances. After a visit to Constanţa in 1839, the British consul to Bucharest, Robert Gilmore Colquhoun, mentioned that the harbour had only about 5–6 feet of water, as the eastern gales and the destruction of the old dyke favoured the accumulation of sand. Only 12–15 small ships could anchor there, but with relatively easy technical works it could host 60 ships of 150–200 tons .
During the 1840s, the town had about 40 dwellings, concentrated in its peninsular part. A foreign traveller described Constanţa in 1843 as a poor village with hovels similar to beavers’ lodges, with ragged women and children, no more than 150 inhabitants in total. A few years later, Ion Ionescu de la Brad  referred to the difficult state of the harbour, which provided no shelter to ships, especially during the cold season. “At Custendje only 8–10 ships a year are loaded with wheat and barley; however, when harvests are rich, their number increases to 25–30 .
The town played an important role during the Crimean War, in the context of the western troops’ landing in the Balkans. In July – August 1854 thousands of allied soldiers died at Constanţa of cholera . A year later two French military missions were quartered there: the first, led by Engineer Charles Lalanne, was to build a road across Dobrudja, useful for provisioning the allied soldiers; the second, led by Intendent Eugene Blondeau, was to requisition hay from the area. According to Camille Allard, the physician of the technical mission , “the best port in Dobrudja is Küstendge, with its simple but well maintained roadstead, which is only open to the southern wind and which would resemble that of Balchich, if it had the same depth. A part of the old dyke still exists; with a slight effort a safe shelter could be obtained for ships of 300–400 tons”. The officer also proposed the completion of port works, which could turn Constanţa into an important commercial entrepot in the Black Sea .
By 1855 the idea of building a canal or a railway between the Danube and Constanţa returned to the attention of western cabinets and investors. The British entrepreneur Thomas Forester referred to the advantages of Constanţa’s position, as its advanced promontory formed a natural shelter for a large area, which “by dredging and delimitation can be turned with moderate expense into a safe and large harbour, capable to receive large ships” . Initially the Porte agreed to the construction of a canal, but in 1857 granted to a British consortium, “The Danube and Black Sea Railway and Küstendge Harbour Company Ltd” (DBSR), the right to build a railway between Cernavodă and Constanţa. The company, with a capital of 300,000 sterling pounds, received a concession for 99 years from the day the railway was operational. Necessary land was given free of charge if state propriety and by indemnity if private property; the investors enjoyed customs and fiscal privileges and immunities for all materials used, facilities extended to ten years for all imports necessary for operating the railway. The same agreement regulated the modernisation of the harbour of Constanţa. By “the convention relative to the port of Kustendge”, the Ottoman Government granted DBSR the right to build on its own expense, risk and danger the harbour with all its facilities, quays, magazines etc., according to plans and projects that were to be presented to the Porte. Necessary port works were to be commonly agreed by engineers appointed by the Ottomans and by those employed by DBSR. The harbour was also leased to the company for a term of 99 years .
The construction of the Cernavodă – Constanţa railway, on a length of 64.675 km, started in 1858 and was completed two years later. The inauguration took place on 22 September / 4 October 1860 (new style). Regarding the port works, the technical project mentioned two dykes, the seawall measuring 836 meters. It was to create a basin and a berthing space with wooden quays on 200 meters, allowing the mooring of about 400 ships. Grain was stored in stone and wooden magazines, as well as in a storied wall magazine built in 1864 . However, works proved difficult and expensive, so that by 1862 the seawall only measured 237 meters . In 1860, in the south eastern corner of the peninsula, Artin Aslan completed a lighthouse, known as the “Genoese lighthouse”. During the next years, the Ottoman authorities and the DBSR leadership had several disputes regarding the completion of the proposed engineering works, but also concerning the development and taxation of maritime trade at Constanţa .
Following complicated negotiations a new convention was concluded on 10 October 1870 between the Porte and DBSR. The Ottomans paid back the leasers the amount of 112,761 sterling pounds, and ships no longer had to pay taxes for entering the harbour. The British company preserved the right to freely use the quays, magazines, etc. in exchange for doing the necessary maintenance works in the harbour and for operating the lighthouse. The company also undertook to prolong the southern dyke according to approved plans. However, DBSR did not hurry to complete these works, and until 1876 it only built 53 more meters of the seawall, whose total length was now 290 meters. The works were insufficient, and the roadstead remained exposed to the strong gales of the Black Sea .
Although it did not work at full capacity, the harbour witnessed a significant development during these decades. In 1863 a total of 421 ships loaded cargoes at Constanţa, among which 131 under Austrian flag, 97 British and Ottoman, 17 Italian. In 1864 it exported about 2.5 million hectolitres of grain. For 1876 statistical data mention 317 ships and 237 steamers. By flag, the largest numbers of ships were Ottoman (180), Greek (84 sailing ships and 11 steamers) and British (74 steamers and 10 sailing ships) .
The town also greatly developed following the British investment. Constanţa consisted of the peninsular part, where local Ottoman institutions were quartered. There were five neighbourhoods (Turkish, Greek, Jewish, Armenian, and British). The British district was placed on the Black Sea coast, and had stone buildings serving as residences for staff and as offices for the company’s administration . Population increased to about 4,000 people, and modernisation was also visible in the introduction of public lighting with petroleum lamps and the organisation of a local police force.
The situation of Constanţa on the eve of the Russian–Ottoman war of 1877–1878 is described by Baron Willem d’Hogguer. The town had a heterogeneous population of about 4,000 people (Greeks, Turks, Tartars, Bulgarians, Romanians, etc.). The harbour was in a poor state, as its seawall was badly built. The depth of the sea (17–18 feet) was insufficient, and large steamers could not berth directly at quays and were forced to complete their cargo in the roadstead, facing dangerous weather conditions. Grain magazines were not sufficient in good agricultural years. Main imports consisted of cotton (England), footwear and clothing (Austria), iron (England and Austria), colonial goods, wine and alcohol (Constantinople), candles, flour and petroleum (America). Besides grain, exports consisted of animals, wool, hides, cheese, etc. Shipping companies such as Messageries Maritimes, Lloyd and Florio operated at Constanţa, and Britain, Belgium, Austria and France had consular representatives in the town.
In July 1877 the Ottoman army and a part of the population left the town, which was readily occupied by the Russian troops. They paid a special attention to defending the harbour, both by sea and by land, and it resisted an Ottoman naval attack .
Constanţa remained under Russian control until late 1878, when, according to the provisions of the Berlin Treaty, Romania took possession of the province of Dobrudja. In November 1878 the Romanian officials got to Constanţa and began to impose the new administration.
 M. D. Ionescu, Cercetări asupra oraşului Constanţa. Geografie şi istorie (Bucharest: Tipografia şi Fonderia de litere Thoma Basilescu, 1897), 51; Valentin Ciorbea, Portul Constanţa de la antichitate la mileniul III (Constanţa: Europolis, 1994), 61.
 Ciorbea, Portul, 61.
 Ionescu, Cercetări, 52; Ciorbea, Portul, 62.
Ionescu, Cercetări, 53–54; Ciorbea, Portul, 62.
 Ciorbea, Portul, 63.
 Ibid., 63–64.
 Ionescu, Cercetări, 55–56.
 Ciorbea, Portul, 66.
 Ionescu, Cercetări, 58–59.
 Ionescu, Cercetări, 60–63;
 Ciorbea, Portul, 68–69.
 Ciorbea, Portul, 70–71.
 Ibid., 71–73
 Ibid., 74; details for Constanţa during this period in Andreea Atanasiu, “Dobrogea sub administraţie otomană. Constanţa şi Tulcea – studiu de caz”, in vol. Dobrogea 1878–2008. Orizonturi deschise de mandatul european, edited by Valentin Ciorbea (Constanţa: Ex Ponto, 2008), 129–133.
 Ciorbea, Portul, 75.
 Ibid., 76.
 Ibid., 76–77.
 Ibid., 77.
 Ibid., 79–80.
 Ionescu, Cercetări, 67.
 Ciorbea, Portul, 80–81.
Atanasiu, Andreea, “Dobrogea sub administraţie otomană. Constanţa şi Tulcea – studiu de caz” [Dodrudja under Ottoman Administration. Constanţa and Tulcea – Case Study”, in vol. Dobrogea 1878–2008. Orizonturi deschise de mandatul european [Dobrudja 1878–2008. Open Horizons by the European Mandate], edited by Valentin Ciorbea (Constanţa: Ex Ponto, 2008), 125–138.
Ciorbea, Valentin, Portul Constanţa de la antichitate la mileniul III [Constanţa Harbour from the Antiquity to the Third Millennium] (Constanţa: Europolis, 1994).
Ionescu, M. D., Cercetări asupra oraşului Constanţa. Geografie şi istorie [Researches on the City of Constanţa. Geography and History] (Bucharest: Tipografia şi Fonderia de Litere Thoma Basilescu, 1897).
Rădulescu, Adrian, Lascu, Stoica, Haşotti, Puiu, Ghid de oraş. Constanţa [City Guidebook. Constanţa] (Bucharest: Sport Turism, 1985).