Monumental theatre buildings such as the royal theatre Carré, facilitate different forms of performance arts and are obliged to maintain the monumental values of the building. Monumental theatres face many challenges. such as growing multifunctionality demands, physical limitations. The research question of this research is "What tool can be designed, resulting in an advice, that futureproofs monumental theatre buildings in the Netherlands, such as the Royal Theatre Carré?’’. The question is answered with a literature study and a case study consisting of interviews and a document analysis. Valuable monumental tools that specify a real estate strategy tool for monumental buildings are the characterization grid and the historical value table. The value which includes the current trends in the Dutch theatre landscape, the most valuable real estate strategy tool for monumental theatres is the DAS-frame. The most important advice for Carré are some management adjustments, a floating theatre, a renovated modernized roof, some sustainability measures and most importantly a second auditorium. The final tool that futureproofs monumental theatre buildings is a combination of the monumental value tool and the theatre trend matrix implemented in the DAS-frame. The result of the tool; the final step by step plan is than the actual strategic advice. Often monumental theatres are already futureproof in a way because the monumental characteristics of the building contribute to a certain experience that visitors desire and that performers desire to perform in.