Which aspect of the roman catholic church established in the 300s remains today? the roman catholic church's leader is still the bishop of rome, or the pope. the roman catholic church remains the official church of the city of rome. the roman catholic church remains the only official church. the roman catholic church's power structure remains unchanged?

The Roman Catholic Church's leader is still the Bishop of Rome, or the pope.

There are many other "official churches" in the world since the split of Eastern Orthodoxy from Rome in the 11th century and the Reformation movements of the 16th century.

Vatican City, the papal enclave within Rome, is the seat of Roman Catholicism. But the whole city of Rome falls under the same policies as the nation of Italy, where Roman Catholicism ceased to be the state religion in 1984.