John gives us a good clue about the place they were in.  I was startled when I first realized what John was writing about. 

Revelation 22:And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb.
2 In the midst of the street of it, and on either side of the river, was there the tree of life, which bare twelve manner of fruits, and yielded her fruit every month: and the leaves of the tree were for the healing of the nations.

Here we learn that the Tree of Life is in the Holy City or in Paradise. It is not visible to mortal eyes alone. 

We learn too that the Waters of Life originate there.  Going back to Genesis, we discover that the one river splits and becomes four.  That alone should tell us it's not the kind of river we see.  Streams on the face of this earth join together to form a river and rivers join to become bigger rivers. 

Genesis 2:10 And a river went out of Eden to water the garden; and from thence it was parted, and became into four heads.
11 The name of the first is Pison: that is it which compasseth the whole land of Havilah, where there is gold;
12 And the gold of that land is good: there is bdellium and the onyx stone.
13 And the name of the second river is Gihon: the same is it that compasseth the whole land of Ethiopia.
14 And the name of the third river is Hiddekel: that is it which goeth toward the east of Assyria. And the fourth river is Euphrates.

Thus all nations had access to the Living Waters since it divided out and came down over the whole earth.  Currently, access is limited for many people who get enough to keep "body and soul" together so they can come to repentance and be saved. 

Why did Adam and Eve make loin clothes for themselves out of fig leaves?  John again gives additional insight, I think.  Not only to cover their nakedness but also to "heal" themselves.

So where is the Holy City now?  It is still coming down, coming down, coming down.  It has been coming down since Genesis.  It is between the Highest Heaven and our earth. When the Holy City contacts the earth, we'll have the marriage of Heaven and earth.  We, here still on the earth, are to prepare ourselves like a bride gets ready for the bridegroom.