If you're a photon, your perspective would be irrelevant.
If you think about it, since no time passes for them being at lightspeed, the moment they burst into existence = the moment they cease to exist.
aka, a billion years ago mr photon was created in a star, travelled a gazzillion kilometers and smacked the rear portion of your retina and ceased to exist.
for the photon, no time passed.
so your answer is : From a photon's perspective, nothing happened because from its perspective it ceased to exist the moment it sprung into existence.
That they travelled that big of a distance without aging is another matter. From the photon's POV, it existed in all points in space that it traveled from its origin point to its termination point.
But since space-time is curved by gravity, and gravity is created by concentration of mass, and everything in the universe is in motion...
the photon travelled in a slight arc the whole way from point A to point B, (probably doing a Sine wave sort of trip as bigger mass objects pulled it to and away from them) And since nothing in nature is curved but rather a series of *very* small straight lines that make up a curve (aka, draw a biiig letter "C" on a chalkboard, then stick your face on any point of the letter "C" ..you will not see a curve but rather a straight line)...
then you could say that, if photons had any perspective they could perceive (remember their lifetime from their frame of reference=0), they would not perceive space-time (since time is 0). If anything, they would perceive their existence as an instant transfer of energy and negligible mass from origin point into termination point.
clear enough?
(now them faster-than light traveling particles have one hell of a trip, but thats another story!)
