first torii gate of a shrine
Refers to the outermost or primary torii gate at the entrance to a Shinto shrine, often the largest and most prominent.
See also: 鳥居
参道を進むと、まず一の鳥居が見えてくる。
As you walk along the approach, the first torii gate comes into view.
一の鳥居をくぐると、そこからが神域です。
Once you pass through the first torii gate, you are on sacred ground.
Compound of 一 (いち, 'first') + の (possessive particle) + 鳥居 (とりい, 'torii gate'). The term follows the traditional numbering of torii gates at Shinto shrines, where the outermost gate is called 一の鳥居.