noun
observation deck; observation room; observatory
Refers to an indoor space, often on a high floor of a building, designed for viewing scenery. Commonly found in towers, skyscrapers, and airports.
東京スカイツリーの展望室から富士山が見えた。
I could see Mt. Fuji from the observation deck of Tokyo Skytree.
空港の展望室で飛行機の離着陸を見学した。
We watched planes take off and land from the airport's observation room.