In a walled garden in Genoa, Italy, where Filippo De Mari Casareto Dal Verme’s family has lived for about 150 years, a massive, mint-green staircase recently appeared. Developed by regional architecture, style, and landscape studio Caarpa, the folly-like structure connects two levels that were formerly signed up with only by a circuitous path. It also includes a glass-encased space where Filippo, a mathematics teacher nearing retirement, plans to “check out, paint, listen to music, do nothing, and sleep.”