ok, ive got a few answers for a couple questions.... yes it was most likely earth that they landed on and seeded, they came back every few thousand years to check on us and leave clues to come visit them, why did they want to send us to their military base?
WELL thousands of years have passed since the last time they came and visited, they came, visited, and everything was peaceful, why WOULDNT they want to invite us to the place that we were created from? who BETTER to deal with their creation, the scientists that created them, or random nobodies in a city, that might, or might not, have any clue?
if i was one of the engineers and i wanted to finally meet the people i had helped create, i would invite them back to my lab, NOT new york city
also, thousands of years have passed, whos to say their lab wasnt a peaceful place the last time they sent someone here and left a clue.. they had a few thousand years to change this engineer lab into a military fortress between then and now.
AND if you spent millions of dollars and time and had all the equipment to make a race of people and went through all that trouble, then something suddenly changes, and you had to go about destroying your creation, are you going to go out and build a new base, or are you going to re-purpose your already existing base, and use all the equipment you already have available at the current location? it just makes sense...
THEN the **** hits the fan and the base is wiped out by the crap your making to destroy your invention.