The former Royal High School is one of Scotland’s most significant sites and arguably the most accomplished Greek-Revival style building in the UK; it is therefore of international cultural heritage significance.

Constructed in the mid 1820s the building is one of Edinburgh’s most important but – at the time the conservation plan was commissioned – also one of its most vulnerable historic buildings. Listed by Historic Environment Scotland in Category A and situated within the New Town Conservation Area and the Old and New Towns of Edinburgh World Heritage Site, it is regarded as the masterpiece of Thomas Hamilton (1784-1858), one of Scotland’s foremost neoclassical architects. It is also one of the focal points of the highly important and prominent Calton Hill natural and designed landscape. The site was adapted in the late 1970s to become the new Scottish Assembly building, including adaptation of the former assembly hall to become the debating chamber. However the 1979 referendum on devolution failed to reach a majority and the assembly never sat.

The conservation plan was commissioned to support the development of the Royal High School Preservation Trust’s and National Centre for Music’s scheme to conserve and adapt the building as a new home for St Mary’s Music School, Scotland’s leading specialist music school. An initial conservation plan was written by Simpson & Brown in 2015 to support the process for the music school scheme, at the time presenting a viable alternative to a proposal to convert the building into a luxury hotel.

The updated and expanded conservation plan research and assessment of significance, completed in May 2022, was awarded the SAHGB and IHBC Heritage Research Award in December 2022.