This is a riddle that seems to be popping up all over the internet right now. I think the source might be a riddling community
However, one suggestion that keeps popping up on forums is the word Erie, which is one of the Great Lakes in the United States - although the explanations as to how that conclusion is reached are varied.
Personally, all that I've managed to work out is that it's a 4 letter word, and that "the end of time and space" refers to the letter E.
I'd like to think that N. Foster's delight refers to a building that Norman Foster might have designed, but since he's responsible for everything from the Gherkin in London through to the design of the Reichstag dome in Berlin - it's hard to pin-point what that might be a reference to...
I'm curious to see what other people can come up with though, so please post your guesses...