Following the death of Eudoxia, the Praetorian Prefect Anthemius took control of the Eastern Empire and ran it wisely for the next decade. Meanwhile in the West, anti-barbarian policies will lead to the invasion of Italy by Alaric.
These, big, ancient Walls I saw several times as I toured around Istanbul. Some are still in ruins, and some have been restored. Evidently, the wall contained 8 main gates. The main public gates led across the moat on bridges, while the secondary gates, traditionally called “Military Gates”, led to the outer sections of the walls.
They are located on the outskirts of Istanbul, built by the Byzantine Emperor Theodosius II (408-450) who expanded the area of his imperial capital of Constantinople by building these great land walls farther out into the country. When finished, the Theodosian Walls were almost 7 kms in length. They were breached only twice: in 1204 by the armies of the Fourth Crusade, and in 1453, a thousand years after they were built! by the gigantic cannon of Sultan Mehmet the Conqueror, after which Constantinople became Istanbul.
In 1894 a disastrous earthquake toppled parts of the walls.
There is also the Palace of the Porphyrogenitus which is a large three-story building located between the inner and outer fortifications of the northern corner of the Theodosian Walls. On the east is the remnant of a balcony. The roof and all of the floors of the structure have disappeared. The remaining walls are elaborately decorated in geometric designs using red brick and white marble typical of the late Byzantine period.
You will have to look at your map to decide where you want to go and have a look at them.