[gamblor956]

You don't mold stone, you chisel it to detail. Concrete is molded, and sanded to detail.

The cost of the mold is proportional to the level of detail required. A plaster mold can be had for a few dollars. A finely detailed mold mimicking a Grecian sculpture...a few tens of thousands. But that is simply because more work goes into preparing the detailed mold, i.e., laser scans of the original, the 3D print and finishing of the negative. This is still much, much cheaper than paying a sculptor for the hundreds of hours it would take to recreate the sculpture by hand.

Concrete buildings have aged poorly because they receive minimal maintenance. That was kind of the point of Brutalist architecture. Stone buildings receiving the same level of maintenance have the same water and rust stains, and mold, but generally because stone buildings are older historic buildings, they receive above-average levels of maintenance and therefore look like they are in better shape.