special observation deck; higher viewing platform
Refers to an elevated observation deck, often above the main deck, offering a premium view. Common at towers and skyscrapers.
I could see Mt. Fuji from the special observation deck of Tokyo Tower.
展望台 is a general observation deck, while 特別展望台 is a higher, premium deck often requiring an extra fee.
Compound of 特別 (special) and 展望台 (observation deck).