Who is this guy?

OK, I have an unresolved issue from my trip to Rome a few months ago.

The first night I was in Rome, I stepped outside my hotel, the Hotel Victoria Roma (which I highly recommend), on the Via Campagna, to try to take in the fact that I was in Rome, a place I've studied for more than two decades, a place that I've loved from afar.

My first order of business was finding one of the famous SPQR manhole covers, which I did around the corner.  But what really struck me was this bust, in an alcove of the Aurelian Wall caddycorner from the Victoria Roma:

Oddly, though the bust is not illuminated, it struck me much more in the dark than the morning I took this picture.  Like I said, it sites in an alcove of the Aurelian Wall, over a stairway leading into a pit that smells like urine, caddycorner (roughly the northeast corner) from the Hotel Victoria Roma on the Via Campagna.

One slight question, however:

WHO IS HE?!?

No one seems to know.  I thought that since this was a bust of a man in the walls built by the Roman Emperor Aurelian (circa 275 AD), it might be, you know, Aurelian.  But one of our daily tour guides (not our main one, who was excellent, but a rather snobbish woman) insisted rather rudely that it was not.

Then who is he? I've not been able to find a definitive answer.

The contestants that I have identified are:

Aurelian -- for the reasons I mentioned above, plus the fact that he seems to be wearing imperial insignia.  While the images I have seen of Aurelian are often inconsistent, they generally show him with hair much shorter than this, and with thinner lips and a harder expression.  Of course, it could be a depiction of Aurelian as ...

Alexander the Great -- the hair and face are consistent with Alexander the Great, and the walls were built during a time when Rome was gaga over anything Greek, especially Alexander the Great (remember the Roman Emperor Alexander Severus), though most Greeks wouldn't consider Alexander Greek.  Problem is the imperial insignia, and his placement in a wall built by Aurelian.

Belisarius -- Roman general who re-conquered parts of Italy for the Eastern Roman ("Byzantine") Empire under the Emperor Justinian.  There may be a local tradition to this effect, as the Hotel Victoria Roma has a restaurant called the Belisario. Local businesses are often named after ancient Roman figures associated with that area.  For instance, the Piazza Navona, a place I loved, has a restaurant called the Cafe Domiziano, named after the rather unpopular Emperor Domitian; the Piazza Navona was built on the site of Domitian's circus.  However, there is only one known image of Belisarius, and that shows him bearded.

Raphael -- this is my own entry.  There really is no logical reason for the Renaissance artist Raphael to have a bust in the Aurelian Wall.  However, when I visited the Pantheon (wonderful area, by the way), inside I saw a bust with what appeared to me to be identical facial and hair features.  Unfortunately, none of the pictures I took inside the Pantheon, an impressive but dark place lit only by the oculus in its famous dome, came out for comparison purposes.  The bust here does look like the head may have been put on separate from the rest of the bust, and perhaps was at some point in time replaced.

OK, that's as far as I can get.

Does anyone know who he is?

UPDATE -- edited to correct some typos that I missed earlier.