“Distressed” Jeans & Exposed Duct Work
In fashion, people are known to pay up for “distressed” jeans and other new clothing made to look used.
In real estate, I suppose the equivalent would be leaving duct work, lighting, and other building “plumbing” exposed — features that give modern buildings a “retro” look.
Of course, the reason all those things are exposed in older buildings is that plumbing, electricity, and central heat and air came later.
Whole sections of Manhattan and other, older U.S. cities were built decades (or centuries) before those amenities were available; when they appeared, the easiest way to retrofit buildings was by running conduits in front of (rather than behind) walls, ceilings, etc.
A century later, what was borne of necessity qualifies (in some circles) as trendy.