Fetching details from the dictionary...
both banks (of a river)
川の両岸に桜が咲き誇る。
Cherry blossoms are in full bloom on both banks of the river.
海峡の両岸をつなぐ橋が開通した。
A bridge connecting both banks of the strait has opened.
その都市は大きな川の両岸に沿って発展した。
The city developed along both banks of the large river.