The two-storeyed re-inforced concrete building was designed by South African-born Cairns architect Vibert McKirdy Brown, and was constructed by contractor VW Doyle.

They offered a full primary school curriculum and extra-curricula classes in French, drawing, painting, needlework, and music (vocal and instrumental) to older girls.

[1] Cairns boomed during the interwar period, and by the end of the 1930s the need for a purpose-designed high school building at St Monica's had become urgent.

Cairns architect VM Brown was commissioned to design a high school, to be erected on land in Abbott Street which the Sisters had acquired in 1922, adjacent to St Joseph's Convent.

The Cairns hinterland Soldier Settlement Schemes of the 1920s, the completion of the North Coast rail link to Brisbane in 1924, the continued success of the local sugar industry, the expansion of wharf facilities, the extensive re-building necessitated by a spate of cyclones in the 1920s and the poor condition of earlier timber structures, combined to produce unprecedented building activity in Cairns in the interwar period.

[1] St Monica's High School, which is set back from Lake Street, is a two-storeyed reinforced concrete building with a rectangular floor plan.

It has a fibrous cement hipped roof and is surrounded on three sides by reinforced concrete verandahs that have been enclosed with the insertion of aluminium windows.

Solid balustrades at first and ground floor levels have indented stripped patterns symmetrically positioned between concrete piers that support the verandahs and project and terminate above the parapet.

[1] The ground floor has two large classrooms that are divided by a central hall which connects to a small attached rear porch and cloakroom.

St Monica's High School Administration Building was listed on the Queensland Heritage Register on 1 July 1997 having satisfied the following criteria.

St Monica's High School Administration Building is significant historically for its close association with the development of Catholic secondary education for girls in Cairns and district since 1941.

Despite internal and external refurbishment as offices, St Monica's High School Administration Building survives largely intact, and is a fine illustration of 1940s tropical architecture in the then fashionable and progressive Moderne style.

St Monica's High School Administration Building has a strong association for the local Catholic community with the work of the Sisters of Mercy in offering secondary education to the girls of Cairns and district in the mid-20th century.