The Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS) is an executive non-departmental public body of the Scottish Government 'sponsored' [financed and with oversight] through Historic Scotland, an executive agency of the Scottish Government. It is one of the country's National Collections.
The RCAHMS is responsible for recording, interpreting and collecting information about the built and historic environment. This information, which relates to buildings, sites, and ancient monuments of archaeological, architectural and historical interest (including maritime sites and underwater constructions), as well as historical aspects of the landscape, is then made available to the public, mainly at no cost.
It was established (shortly ahead of parallel commissions for Wales and England) by a Royal Warrant of 1908, which was revised in 1992
The website is 
More information on the Wikipedia page