Choose the correct answer:
I loved the museum (which / where) we visited last year.
"Which" usually introduces a parenthetical clause, an informational "aside," rather than the minimal "meaning" of the sentence.
"That" is used for a necessary part of the sentence. It points out the item you are talking about.
Example:
The shoes
, which are on sale, are near the entrance.
(The shoes -- which by the way happen to be on sale today -- are near the entrance.)
The shoes
that are on sale are near the entrance. (pointing to the sales items)
(Other shoes -- the ones that are not on sale -- are at the back of the store.)
----------------------
So if you want to use "which," it will mean:
> I loved the museum, which (by the way) you will recall Mary and I visited last year.
I loved the museum
, which we visited last year.
If you don't want to say that, but instead want to point at the museum, use THAT.
> I loved the museum that we visited last year.