The Metropolitan Museum of Art was founded in 1870. The Restoration of the Fifth Avenue façade presented many challenges in balancing modern intervention with traditional restoration procedures. The selection, testing and ultimate adoption of Saint Astier® Natural Hydraulic Lime mortars was based on ASTM, British Standards and European Norms. The masonry had suffered significant damage from the use of high-strength cement based mortar.
The Restoration of the Fifth Avenue Facades of the Metropolitan Museum of Art (pdf) by Timothy Allanbrook and Kyle C. Normandin, APT International Bulletin, Vol. XXXVIIII, No. 4.