I went through the gate and came out onto the main street.

Literal

Gate [obj-を] pass-through-[and-て] main-street [to-に] came-out.

Two motion verbs chained sequentially. 通る takes the traversed area with を. 出る ('exit, emerge') pairs with に for the destination of exit. 表通り ('main street, front street') is the main thoroughfare, contrasted with 裏通り ('back alley').