In the Netherlands, the Royal Picture Gallery Mauritshuis in The Hague dug down, nestling expansion space underground, resulting in a renovation that “actually doubles the size of the museum without spoiling its allure.”
“This project was all about logistics. It is more about organizing and cleaning up than about design …”
— Architect Hans van Heeswijk to Architectural Record, February 2015
The Frick’s current proposal calls for a below-grade auditorium, which they have considered in the past, according to a 2010 New York Times article. The article describes the enclosure of the north portico for additional gallery space, noting that the Frick had also “considered more grand schemes, including underground galleries beneath its Fifth Avenue garden …”