What controlled vocabulary format should I use to describe specific rooms within a notable building?

Library of Congress Authority File (LCAF) is based currently based on Research Description and Access (RDA); which replaced the Anglo-American Cataloging Rules (AACR) 1^st and 2^nd editions. Here’s some examples of LCAF rooms from the Library of Congress Subject Headings (LCSH).

Oval Office (White House, Washington, D.C.) https://lccn.loc.gov/sh2009005676

Richard K. Armey Room (United States Capitol, Washington, D.C.) https://lccn.loc.gov/sh2003006414

Sala Bologna (Vatican Palace, Vatican City) https://lccn.loc.gov/sh2012001917

You can propose new LCSH to be added: https://www.loc.gov/aba/cataloging/subject/lcsh-process.html

Getty’s Art and Architecture Thesaurus might also be useful http://www.getty.edu/research/tools/vocabularies/aat/

One of the main issues when deciding upon a controlled vocabulary, is if you will link to other institutions, collaborative projects, or internal systems through that controlled vocabulary. If the answer is yes, then the existing standards should be used as much as possible and collaborate with the owners of those systems to find out their standards and requirements. If not, then you can form the controlled vocabulary as suits your needs, as long as it is consistent.

Also, make sure the computer programs will be able to handle the chosen controlled vocabulary, as some won't interpret certain characters in the same way or inhibit access.