This document provides a report on the architectural documentation of the annex building of the former Istana Negara in Kuala Lumpur, Malaysia. The annex building was constructed in 1980 to house the Balairung Seri, or throne room, and was documented through measured drawings, photographs, and written analysis. The report describes the architectural style of the annex building, which incorporates both British colonial and Malaysian influences, and provides historical context on the site and its significance as a royal palace.