Katoomba High School will celebrate its centenary in August.
An open day will be held on August 10 to remember the school's history, experience the school as it is today and to entertain a view of the future.
As far back as 1883, local residents lobbied the Department of Education to upgrade school accommodation and to provide secondary education for children.
Thirty-six years later, Katoomba District School was established, removing the need for students to travel to Parramatta for high school, opening its doors with an enrolment of 61 students.
Prior to this, Upper Mountains students had to leave Katoomba railway station at 6.24am, not returning to Katoomba until 8.06pm, said Katoomba High teacher Nick Long.
Bolstered by the success of the school opening, parents and community members lobbied for the school to have the Leaving Certificate and by 1923, the initial group of Fifth Year students attained their Leaving Certificate.
"As a consequence, parent and community activism helped open up opportunities for those in the Upper Mountains and set in motion a series of progressive changes for the school," Mr Long said.
There was a rapid growth in enrolments, from 400 students in 1943 to 700 in 1958.
"The Parents and Citizens Association were relentless in their aim to have the most modern facilities which could provide for growing enrolments," Mr Long said.
Politician J H Robson, speaking to Katoomba parents and community in 1958, promised to provide "the most modern facilities for secondary education students" and made the promise that there would be provision for a wide variety of sources, so that the needs of every child could be catered for.
Martin Street in Katoomba was chosen as the new location for the ever-expanding school.
Work began on the building, a modernist structure of "reinforced concrete with walls largely of glass set in aluminium frames together with porcelain enamel infill panels."
Despite some big thinking and planning, further population growth meant that new internal facilities were added including a music room, staff study and an extra science lab.
A state of the art library was constructed in the 1980s, which reflected a proactive approach to ensuring the future needs of the new generation of information and technology-hungry students.
"The tennis courts, hospitality facilities, new science laboratories, dance and performing arts facilities, technology hubs and Birriban outdoor learning space, are all testimony to the actions initiated by the school community in recent years," Mr Long said.