NOTE: Tokoro ga is always used after the -ta form of a verb. The tense of this verb, however, is not necessarily past, but is determined by the tense of the verb in the main clause.
1. Used between two clauses indicating that they are opposed in meaning: the result is often unexpected (a. bad result; b. good result): "but, although, when."
a.)Indicating a bad result.
Ginkō e itta tokoro ga, mō shimatte ita.
I went to the bank, but it was already closed.
[When I got to the bank, it was already closed.]
Ano hito ni ai ni itta tokoro ga, kaigi-chū de aenakatta.
I went to see her, but I couldn't because she was in a meeting.
b.) Indicating a positive result.
K daigaku ni wa gōkaku dekinai to omotte ita tokoro ga, gōkaku tsūchi ga kita.
Although I thought I wouldn't pass [the entrance exam to] K University, I received a notice that I had.
Amari kitai shite inakatta tokoro ga, sono konsāto wa subarashikatta.
Although I hadn't really been expecting much, the concert was fabulous.
Hope this helps!
°˖ ✧◝(○ ヮ ○)◜✧˖ °こゆうきあいはら°˖ ✧◝(○ ヮ ○)◜✧˖ °