One of the most mind-boggling things to me is spacetime itself grows larger by the minute. That's the 4 dimensions we normally think of, the 3 of space and 1 of time. All expanding. The fabric is expanding, not just the things embedded in it.
The night sky is absolutely full of wondrous and astounding things. Things that can't be seen without telescopes. If you really are interested search for an astronomy club near you and attend one of their public viewing nights.