？
Did you go to any famous gardens?
Literal
Somewhere famous-[attributive-な] gardens [to-に] go-[past-った]-[question-の]?
どこか ('somewhere, anywhere') is the indefinite-location indefinite — built from the interrogative どこ (where) + か (indefinite marker). Makes the location non-specific. A casual follow-up question after learning someone took a trip. 庭園 ('garden, landscape garden') is more formal than plain 庭 and used for designed/famous gardens.