By the time a wealthy Rio couple hired architect Marcio Kogan and his associates to dream up a summer retreat for them, their house was already taking form. There’s a certain template that any right-minded architect would follow when building in the mountains north of Rio, where only rounded granite peaks interrupt the thick weave of rain forest. The landscape–rife with ferns and high, thin trunks–resembles Rio’s site when it was still wild and undeveloped. Part of the Atlantic Rain forest, this area rivals the Amazon in density and diversity of vegetation. Given the lushness and the privacy it affords, it’s best to let jungle be jungle: Build a terrarium in reverse–a viewing platform raised on stilts and nestled into the tree canopy’s green shadows.