The Arch of Constantine is right next to the Colosseum.

The remains of the Ludus Magnus, where the gladiators trained.

The Roman Forum.

Details of the Arch of  Septimus Severus

The two lads who started it all, with their step-mother.   

The Theatre of Marcellus.
It looks a bit like the Colosseum, but someone built their house on top of it.    

The temple of Romulus is another contender for the world's oldest doors.    

The Emperor Trajan built his own Forum, the most complete part being Trajan's Markets.   The tourists seem to miss this.

Trajan's column.

and the column of Marcus Aurelius   

Both have had their statues replaced.  One with Peter, one with Paul.

The Palatine hill is not to be missed.

The Baths of Carracala are another must see.

We also enjoyed a visit to the Domus Aurea, but it is underground and no photos.