Thing = 물건
Building = 건물
I thought I had enough problems learning Korean...
I actually like this as it is easier to memorize. When you don't know one you may remember that it's the other one with the syllables swapped.
Remember that 저 means "that over there." 저 can also mean, "that," but its more common to use "저" for "that over there."
Dont get confused with "물건" and "건물" Since the words are swapped, it can make the two nouns confusing. So you have to remember, that "물건" means THING and "건물" means BUILDING.
And if you remember from Adjectives 1, "큽니다 " means big.