Constantinople was a largely populated city that was a rich city too. It was the capital to the Roman Empire because it was easy to protect and defend. They also created a sewer system.
Conflict Between East & West
When the city was on fire, Justinian and Theodora hid in a palace. After the city burned, he was determined to restore how it was but even better. He rebuilt Constantinople and launched military campaigns. He then created a "systematic body of law" which is known as one of the most organized systems of laws.
Eastern Orthodox originated because of the Byzantines. They believed it was more than a religion, but rather a foundation of their empire. Like Catholics, they had a supreme authority in the church.
There was war between the East and west because of religious purposes. The west's Christianity was based around Jesus as the east's Christianity wasn't. Later on Cerularius closed all churches that worshiped western tradition.