Architect Annabelle Selldorf and interior designer Matthew Frederick recently revamped Faircourt , a luxurious Tuscan-style villa in New Jersey, for a couple and their two children. The architect and designer’s task was to take a 30,000-square-foot mansion constructed in 1897 and make it work for a modern family. Here are a few lessons Selldorf and Frederick learned along the way.

Do more with less. Fredrick’s sparing deployment of clean-lined, generously scaled contemporary light and furniture allows elaborate architectural elements to take center stage.

Light fantastic. To illuminate the previously dim interiors, Selldorf sensitively widened original windows and did away with opaque exterior doors in favor of glass replacements.

Mix it up. The architect also transformed the old service wing and loggia into a magnificently modern kitchen and family room while preserving grand arched doorways and windows as allusive historical footnotes.