Very interesting stuff. I have my own (wild) speculation on some of the AI in Destiny. It has probably been brought up before, but it wouldn't surprised me if AIs are based on seriously injured or killed humans from the past, so we put their consciousness in a robotic body. To me this would fit nicely with the two other races we already have, since they are both just variations on humans. Also could explain where Ghosts come from as well as maybe how we can be revived?

We’ve seen evidence of massive cities on Mars, on icy moons, on the once deadly surface of Venus, and even on the sun blasted face of Mercury. How one even begins to terraform Mercury just boggles the mind!

I think you're right, but I think it's not so much its closeness to the Sun as its small size that makes it a bad candidate for terraforming (at least in the relatively short term; if and when the Sun gets close to the end of its life and expands to humongous proportions, Mercury will be the first to go-- followed by Venus and possibly Earth).

I imagine the Golden Age of Humanity as not too dissimilar to what we have today. Relatively widespread peace and large pockets of prosperity. There would have been great feats of exploration and breakthroughs in science, but there would have also been conflict. From what’s left of the Fall we see that Humanity still knew how to build tanks and aircraft carriers. Are we to think that the Charlemagne a Warmind machine intelligence (aka AI) built on Mars was the only one of its kind? We hadn’t come together as one people and rejected our warlike ways, that much seems as certain as our expansion into the solar system.

Of course not, it said that was one of the great Warminds of the Golden Age.

Looking at the ruined remains of the cities on Mars, Venus, and Mercury it seems obvious that the Golden age was just that, an age. Unless we mastered Star Trek like replication on building sized scales the cities we’ve seen on other worlds would have taken decades if not centuries to build, not even counting the time to transport enough colonists there to build them.

eh, maybe
I would think building techniques and technologies would grow right along with travel, weaponry, etc., so I think it would at least be not much more than today (i.e. a few years, up to a decade for a particularly large building).

- While we have pretty good proof that The Traveler was responsible for making the rest of our solar system livable, but I think maybe that’s not enough to launch Humanity into a 200+ year age of expansion. If The Traveler terraformed our worlds today in 2013 would we have the technology and resources to expand? Not really. Sure we might send a few astronauts, but city building, on moons of Saturn and Jupiter? Nah, that would be hugely, prohibitively expensive. We don’t have the lift capacity to get big equipment into space, and we don’t have the speed to make trips to anything past Mars even remotely manageable. Because of this I posit that The Traveler also brought the gift of faster than light travel. Journeys that would have taken months (to Mars) or years (to pretty much anywhere else) would have been cut down to minutes, hours, or days. Terraforming is great, but FTL is how you kick start a Golden Age!

I would like for FTL to be present or at least exist, but I don't think it would be needed for this. If the planet or moon is already livable, we could just send a large enough group of people there with some food and resources. They could, depending on the place, mine, build, farm, and make whatever else they might need, grow their population safely, and communicate with (most of) the rest of humanity with a maximum of... I had "a few days' delay" here and went to look stuff up and do math and it would actually be a maximum of about 4 hours and 15 minutes provided you stay near the major planets (that's Neptune to Earth at their farthest points from each other), but our travel speed at present is pretty abysmal, more than I thought, although it depends what you take as the fastest we've made something go, whether you want to include the gravity slingshot move, and how slowly you'd have to build up and lose speed for humans to survive the acceleration. Anyway here's a handy table of travel times around our solar system and here's something to give us hope for FTL.
Also, where did you get the "200+ years" figure?

- What was our civilization like during the Golden Age? Was Earth a sole authority over dozens of colonies? Did each planet and moon get to govern itself? Were planets carved into sections controlled by competing countries back on Earth or rebellions that had broken away? Did all of the above try to occur at the same time? The Powers of Mars seems to have been a thing, and it sounds pretty serious. Was it a government or a megacorp or just a rural province with an awesome name?

I don't know, but now I'm more curious about what it was.

- What about the Exo and Awoken? Did they exist during the Golden Age? I’ve always thought of Exo as proof of widespread AI and perhaps even AI citizenship. It doesn’t make a lot of sense for one to be able to play as a robot if one doesn’t have all the rights and access of a regular ole Human. And the Awoken? What about them?

I don't know, and I'm just as curious as I was before (which is to say, very).

- And finally, The Traveler eventually saved us, but why did it help us in the first place? Was our Golden Age a gracious gift? Or could it have been a secret bargain that eventually brought both us and The Traveler a world of hurt? I fully expect a twist with the Traveler, who’s to say it was a force for good at all? Or that we were?

I have a feeling the game, maybe the whole series, will hinge on the answer to that question, assuming we don't find out until the game's released. Then again, I also have a feeling it'll be one of those things that will have a few clues but no real answer present and won't matter to the story so it'll basically be there for people to make theories about.

My only thing to add would be this:

We see fields of rusty, wrecked equipment - cars and planes in particular - in several sources. Above all, I'm thinking of this bit of concept art:

The planes here look very old. The one up close looks almost like Korean War technology (think F-86 Sabre), and the one in the background (mostly covered up by the foreground) looks like World War II technology (sort of like a P-38 Lightning)! When on earth were these even made?

Those cars don't look futuristic. Rather, they look quite similar to cars from today, or even from a few decades earlier! Again, when were these made?

Any ideas?

Vale,
Perseus

What if The Traveler was meant to help Planets or entire Solar Systems but with its help it brought with it harm? Maybe it would help a Planet in distress and raise them to great heights but it would be followed by the Civilization(s) it had rescued before and had promised great things (like the Fallen, who feel entitled to Earth). They would follow the Traveler seeking the things it had promised before it left them and maybe when the Traveler touched a new Solar System the previous Civilization(s) all felt entitled to it and would fight to get it.

Derp. I made this before I finished reading the whole thread, and this is almost exactly what he said. XD

I think what I'm most curious about as far as this stuff right now is whether or not the facility we were shown was the Baikonur Cosmodrome (or part of it or connected to it or built on top of it or built from it).
Also, I noticed in the concept art and game screenshots all the tires are gone; I forgot how long that takes but it gives us a minimum for the length of time between the collapse of civilization and the point we (the player characters) enter the story.