If a sentence in parentheses follows a sentence, place a period before the closing parenthesis:

I went to an exhibit at Vito Schnabel’s gallery. (Vito is the son of the artist Julian Schnabel.)

If a phrase or clause in parentheses concludes a sentence, place a period after the closing parenthesis:

I went to an exhibit at the gallery of Vito Schnabel (son of the artist Julian Schnabel).

I went to an exhibit at the gallery of Vito Schnabel (who was the son of the artist Julian Schnabel).