The first school building was inspired by the School Founder Mr Ross Booth from the design of a farmhouse in Eugowra Central West, NSW. Ross Booth had seen the “Eugowra Farmhouse" in a magazine with its domed roofing, one level reinforced concrete slab, and adopted the design for the School.
Construction of the first classroom block commenced in late October 1982.
Fox and Associates, Architects/Planners submitted to Baulkham Hills Shire Council in May 1982 to erect a complete primary and secondary co-educational non-denominational school. The surveyor was Mr Roger Beeston and Paynter and Dixon Pty Ltd were the builders. Concern was expressed regarding whether the construction would be ready for the first term classes in 1983, however, it was completed just in time as the first students arrived for lessons at 8.30am on 7 February 1983.
The building housed; four classrooms for secondary school students in Social Science, a Science preparation room, a store room, a staff room with a Resource Centre located around the rooms, and the corridor with two slow combustion heaters.
Artist Frank Hodgkinson's 1989 lithograph of The Hills Grammar School's first building was reproduced onto school stationery in 2002. Throughout the years the School’s first building has been modified, renovated and used for many different faculties changing its original design and use. In 2016 a major refurbishment and upgrade brought back some of the original concepts with corridor space reinstated. It is now known as the Languages Building.