Firstly, it can be said that it was not Nero. It would have helped immensely if the choices were given. "Constantine" was the roman emperor who had an arch built in his name. I hope that this is the answer that you were looking for and the answer has actually come to your desired help.
The "Arch of Constantine I" was erected in c. 315 CE. It is a triumphal arch, built in Rome to commemorate Constantine I's victory over Maxentius at the Battle of Milvian Bridge.
