1) Constantine I was a Roman emperor who legalized Christianity.

2) Constantine I is also known as Constantine the Great.

3) Constantine I established the city of Constantinople as the new capital of the Roman Empire.

4) Constantine I defeated his rival Maxentius at the Battle of Milvian Bridge.

5) The reign of Constantine I marked a significant shift towards Christianity in the Roman Empire.

6) Constantine I was the first Roman emperor to convert to Christianity.

7) Constantine I issued the Edict of Milan, granting religious tolerance to Christians.

8) Constantine I is remembered for his military campaigns and administrative reforms.

9) Constantine I was declared Augustus of the Roman Empire in 306 AD.

10) Constantine I's rule brought about major changes in the Roman Empire's politics and religion.