In the year 328 of our era, Constantine commenced the transformation of Byzantium into New Rome by widening the boundaries of the ancient town and erecting new fortifications.
On foot, spear in hand, the emperor traced the limits of the future capital in person, and when his courtiers, surprised at the compass of the circuit he set himself to describe, inquired how far he would proceed, he replied, “Until He stops Who goes before me.”[[40]] The story expresses a sense of the profound import of the work begun on that memorable day. It was the inauguration of an epoch.
We shall endeavour to determine the limits assigned to the city of Constantine. The data at our command for that purpose are, it is true, not everything that can be desired; they are often vague; at other times they refer to landmarks which have disappeared, and the sites of which it is impossible now to identify; nevertheless, a careful study of these indications yields more satisfactory results than might have been anticipated under the circumstances.
The new land wall, we shall find, crossed the promontory[[41]] along a line a short distance to the east of the Cistern of Mokius on the Seventh Hill, (the Tchoukour Bostan, west of Avret Bazaar), and of the Cistern of Aspar at the head of the valley between the Fourth and Sixth Hills, (the Tchoukour Bostan on the right of the street leading from the Mosque of Sultan Mehemet to the Adrianople Gate). The southern end of the line reached the Sea of Marmora somewhere between the gates known respectively, at present, as Daoud Pasha Kapoussi and Psamathia Kapoussi, while its northern extremity abutted on the Golden Horn, in the neighbourhood of the Stamboul head of the inner bridge. At the same time the seaward walls of Byzantium were repaired, and prolonged to meet the extremities of the new land wall.
That this outline of the city of Constantine is, substantially, correct, will appear from the information which ancient writers have given on the subject.
(a) According to Zosimus,[[42]] the land wall of the new capital was carried fifteen stadia west of the corresponding wall of Byzantium. The position of the latter, we have already seen, is marked, with sufficient accuracy for our present purpose by the porphyry Column of Constantine which stood close to the main gate of the old Greek town.[[43]] Proceeding from that column fifteen stadia westwards, we come to a line within a short distance of the reservoirs above mentioned.
(b) In the oldest description of Constantinople—that contained in the Notitia[[44]]—the length of the city is put down as 14,075 Roman feet; the breadth as 6150 Roman feet. The Notitia belongs to the age of Theodosius II., and might therefore be supposed to give the dimensions of the city after its enlargement by that emperor. This, however, is not the case. The size of Constantinople under Theodosius II. is well known, seeing the ancient walls which still surround Stamboul mark, with slight modifications, the wider limits of the city in the fifth century. But the figures of the Notitia do not correspond to the well-ascertained dimensions of the Theodosian city; they fall far short of those dimensions, and therefore can refer only to the length and breadth of the original city of Constantine. To adhere thus to the original size of the capital after it had been outgrown is certainly strange, but may be explained as due to the force of habit. When the Notitia was written, the enlargement of the city by Theodosius was too recent an event to alter old associations of thought and introduce new points of view. “The City,” proper, was still what Constantine had made it.
The length of the original city was measured from the Porta Aurea on the west to the sea on the east. Unfortunately, a serious difference of opinion exists regarding the particular gate intended by the Porta Aurea. There can be no doubt, however, that the sea at the eastern end of the line of measurement was the sea at the head of the promontory; for only by coming to that point could the full length of the city be obtained. Consequently, if we take the head of the promontory for our starting-point of measurement, and proceed westwards to a distance of 14,075 feet, we shall discover the extent of the city of Constantine in that direction. This course brings us to the same result as the figures of Zosimus—to the neighbourhood of the Cisterns of Mokius and Aspar.
Turning next to the breadth of the city, we find that the only portion of the promontory across which a line of 6150 feet will stretch from sea to sea lies between the district about the gate Daoud Pasha Kapoussi, beside the Sea of Marmora on the south, and the district about the Stamboul head of the inner bridge on the north; elsewhere the promontory is either narrower or broader. Hence the southern and northern extremities of the land wall of Constantine terminated respectively, as stated above, in these districts.
From these figures we pass to the localities and structures by which Byzantine writers have indicated the course of Constantine’s wall.