Giants and Allagans

[Enkidoh]

Well, I don't think Acheron is really an accurate representation of what he once was in life, given the fact it was stated he was 'reborn', or rather 'rebuilt' after death to serve as a guardian of the tower.

EDIT: I've looked through my screenshots of the cutscene that plays after completing the Labyrinth of the Ancients for the first time for clarification about what Acheron once was, and this is what I found:

G'raha Tia: "...A giant of a man wielding a shimmering scimitar you say? Yes, that would have been Acheron. He was a hero of the Allagan revolution."
Cid: "And you gleaned that from what exactly? His choice of weapon?"
G'raha Tia: "Well I am a historian. And I have a certain, shall we say, affinity, for the lore of the Allagan Empire."
G'raha Tia: "It is, of course, all knowledge gleaned from musty scrolls and tomes. The ancient texts claim that the Crystal Tower is defended by the champions of eld, ressurected and augmented through the Allagans' extraordinary technology."

Also, during the cutscene of the meeting back at Saint Coinach's Find after leaving the Tower, there's this bit of info:

Rammbroes: "According to <insert player name here>'s account, the labyrinth's defenses were most emphatically active. Disturbingly, <his/her>'s report also mentions a violent encounter with a sentry heavily augmented by Allagan technology."

And when you remember Nael was meant to be an Allagan descendent, and he (or she, the jury is still out on exactly what Nael's canonical gender really is!), was only an elezen of average height. Plus the Ultima Weapon was built by the Allag and the control cabin in it's head was barely big enough to hold Gaius, a mere hyur! So yeah, I disagree the giants/gigas are Allagans.

Instead, I'm thinking it's entirely possible that the giants might have been created by the Allag during their heyday, and rebelled (remember their cousins the hecatonchiers did the same thing thousands of years later in Ul'dah during the Thorne Dynasty). It's appears to me at least they were simply exploited as a source of manual labour. The reason they're obsessed with the Crystal Tower might stem from the fact they probably helped build it, and some kind of cultural memory passed down through generations has been retained, albeit twisted, into an obsession with the place they no longer understand.