Question: What was the Byzantine capital?

Context paragraphs:
Partitio terrarum imperii Romaniae: The Partitio terrarum imperii Romaniae (Latin for "Partition of the lands of the empire of "Romania" [Byzantine Empire]) was a treaty signed amongst the crusaders after the sack of the Byzantine capital, Constantinople, by the Fourth Crusade in 1204.  It established the Latin Empire and arranged the nominal partition of the Byzantine territory among the participants of the Crusade, with the Republic of Venice being the greatest titular beneficiary.  However, because the crusaders did not in fact control most of the Empire, with local Byzantine Greek nobles establishing the Byzantine successor kingdoms (Empire of Nicaea, Empire of Trebizond, Despot of Epirus), most of the crusaders' declared division of the Empire amongst themselves could never be implemented.

Battle of Constantinople (1147): The Battle of Constantinople in 1147 was a large-scale clash between the forces of the Byzantine Empire and the German crusaders of the Second Crusade, led by Conrad III of Germany, fought on the outskirts of the Byzantine capital, Constantinople.  The Byzantine emperor Manuel I Komnenos was deeply concerned by the presence of a large and unruly army in the immediate vicinity of his capital and of the unfriendly attitude of its leaders.  A similarly sized French crusader army was also approaching Constantinople, and the possibility of the two armies combining at the city was viewed with great alarm by Manuel.  Following earlier armed clashes with the crusaders, and perceived insults from Conrad, Manuel arrayed some of his forces outside the walls of Constantinople.  A part of the German army then attacked and was heavily defeated.  Following this defeat the crusaders agreed to be quickly ferried across the Bosporus to Asia Minor.

Nea Ekklesia: The Nea Ekklēsia (Greek: , "New Church") was a church built by Byzantine Emperor Basil I the Macedonian in Constantinople between the years 876–80.  It was the first monumental church built in the Byzantine capital after the Hagia Sophia in the 6th century, and marks the beginning of the middle period of Byzantine architecture.  It continued in use until the Palaiologan period.  Used as a gunpowder magazine by the Ottomans, the building was destroyed in 1490 after being struck by lightning.  In English usage, the church is usually referred to as The Nea.

Transmission of the Greek Classics: The introduction of Greek philosophy and science into the culture of the Latin West in the Middle Ages was an event that transformed the intellectual life of Western Europe.  It consisted of the discovery of many original works, such as those written by Aristotle in the classical period.  Greek manuscripts had been maintained in the Greek-speaking world in Constantinople, the Near East and Egypt.  Interest in Greek texts and their availability was scarce in the Latin West until traffic increased to the East, particularly the medieval Islamic world from where Arabic translations were translated to Latin, and the Byzantine Empire during the time of the Crusades and the Latin rule of Constantinople following the sack of the Byzantine capital in 1204 during the Fourth Crusade.  Finally, the Fall of Constantinople in 1453 to the Ottoman Empire caused many Byzantine Greek scholars to flee to Western Europe bringing with them manuscripts of classical works in the original Greek, thus fueling the Renaissance.

Byzantine beacon system: In the 9th century, during the Arab–Byzantine wars, the Byzantine Empire used a system of beacons to transmit messages from the border with the Abbasid Caliphate across Asia Minor to the Byzantine capital, Constantinople.

Sack of Constantinople (1204): The Sack of Constantinople or Siege of Constantinople occurred in 1204 and marked the culmination of the Fourth Crusade.  Mutinous Crusader armies captured, looted, and destroyed parts of Constantinople, the capital of the Byzantine Empire.  After the capture, the Latin Empire was established and Baldwin of Flanders was crowned Emperor Baldwin I of Constantinople in the Hagia Sophia.

Byzantine–Venetian war of 1171: The Byzantine–Venetian War of 1171 was fought between the Byzantine Empire and the Republic of Venice as a result of the Byzantine imprisonment of Venetian merchants and citizens across the Empire.  10,000 Venetians were imprisoned in the Byzantine capital, Constantinople, alone.  Despite Doge Michiel's apparent will to pursue a peaceful solution, outrage in Venice itself swung popular opinion in the favour of full scale war against Byzantium.  Doge Michiel had no choice but to set out for war, which he did in mid-late 1171.  After indecisive battles in Euboea, Michiel was forced to withdraw his fleet to Chios.  After a number of months on Chios, whilst waiting for a Venetian embassy to be received in Constantinople, plague began to set in.  However, the emperor of Byzantium, Manuel I Komnenos, was well aware of the plague, and continued to stall negotiations.  The Venetians attempted to move from island to island to avoid the plague.  Doge Michiel's efforts, however, were fruitless, and in May 1172, he returned to Venice with what was left of the fleet.  The Venetians were decisively defeated.

Battle of Sarus: The Battle of Sarus was a battle fought in April 625 between the East Roman (Byzantine) army, led by Emperor Heraclius, and the Persian general Shahrbaraz.  After a series of maneuvres, the Byzantine army under Heraclius, which in the previous year had invaded Persia, caught up with Shahrbaraz's army, which was heading towards the Byzantine capital, Constantinople, where his forces would take part in its siege together with the Avars.  The battle ended in a nominal victory for the Byzantines, but Shahrbaraz withdrew in good order, and was able to continue his advance through Asia Minor towards Constantinople.

Battle of Constantinople (922): The Battle of Constantinople was fought in June 922 at the outskirts of the capital of the Byzantine Empire, Constantinople, between the forces of the First Bulgarian Empire and the Byzantines during the Byzantine–Bulgarian war of 913–927.  In the summer the Byzantine Emperor Romanos I Lekapenos sent troops under the commander Saktikios to repel another Bulgarian raid at the outskirts of the Byzantine capital.  The Byzantines stormed the Bulgarian camp but were defeated when they confronted the main Bulgarian forces.  During his flight from the battlefield Saktikios was mortally wounded and died the following night.

Abbasid invasion of Asia Minor (782): The Abbasid invasion of Asia Minor in 782 was one of the largest operations launched by the Abbasid Caliphate against the Byzantine Empire.  The invasion was launched as a display of Abbasid military might in the aftermath of a series of Byzantine successes.  Commanded by the Abbasid heir-apparent, the future Harun al-Rashid, the Abbasid army reached as far as Chrysopolis, across the Bosporus from the Byzantine capital, Constantinople, while secondary forces raided western Asia Minor and defeated the Byzantine forces there.  As Harun did not intend to assault Constantinople and lacked ships to do so, he turned back.

Supporting paragraphs: Transmission of the Greek Classics Sack of Constantinople (1204)
Answer: Constantinople