grandeur, splendor, marvel, wonder, magnificence
These words are similar, but as with so many English words, can also be used differently too.
They are standard words known to all native speakers.
magnificence - a quality of something being magnificent, ... also introducing his Magnificence, the King
splendor, - a quality of something splendid - this seems to suggest ornate, showy
Very similar.
grandeur, - a quality of something being grand, technically big, but also means similar to the others.
marvel, - more general. It means you are surprised/impressed by something, (also a verb, to marvel (at something))
wonder, - more general. It means you think about something, possibly with surprise, (also a verb, to wonder (at/about something))
Check the dictionary for sublties. :)