The crossword solution for the term 'Superhighway Service Site' is 'PLAZA'. A PLAZA is an open public space, typically in a city or town, usually surrounded by buildings. It is often used for public events such as concerts, festivals, and other gatherings. Plazas are also often used as a place to rest and relax, with benches and trees providing shade. Plazas are often found near important landmarks, such as government buildings, churches, and monuments.