The Mese started at the Milion monument
Close to the Hagia Sophia, and basilica cistern led straight westwards. It passed the Hippodrome and the palaces of Lausos and Antiochus, and after ca. 600 meters reached the oval-shaped Forum of Constantine where one of the city's two Senate houses stood. This stretch of the street was also known as the Regia Ῥηγία, "Imperial Road"), as it formed the original ceremonial route from
the Great Palace and the Augustaion square to the forum of the city's founder.
From there, the street continued to the square Forum of Theodosius or Forum of the Bull (Forum Tauri), as it was also known. In about the middle of this stretch, the great mall known as Makros Embolos joined the Mese. At their junction stood a tetrapylon known as the Anemodoulion ("Servant of the winds").
Shortly after it passed the Theodosian Forum, the street divided in two branches at the site of the Capitolium: one branch going northwest, passing by the Church of the Holy Apostles, towards the Gate of Polyandrion, while the other continued southwest, through the Forum of the Ox (Forum Bovis) and the Forum of Arcadius towards the Golden Gate, where it joined the Via Egnatia.
The Mese was 25 metres wide and lined with colonnaded porticoes which housed shops. The Mese was the route followed by imperial processions through the city at least until Comnenian times. The most characteristic was the triumphal entry of a victorious emperor, who entered the city through the Golden Gate and followed the Mese to the Great Palace, while jubilant crowds lined along the street would greet him and the imperial army back home.
The name of this subterranean structure derives from a large public square on the First Hill of Constantinople, the Stoa Basilica,
beneath which it was originally constructed. Before being converted to a cistern, a great Basilica stood in its place,
built between the 3rd and 4th centuries during the Early Roman Age as a commercial, legal and artistic centre