As some of you know, I used to work at a shop that did architectural renderings and house portraits for the real estate market. We used real pencils and watercolors as well as technical pen and ink. I worked there full-time from 1988 to 1991 and did auxiliary work for them till about 1993. Our house art could be seen in real estate ads in the Washington Post and other more upscale advertising magazines.
During my time there we got our first computer and started using it for architectural drawing. I didn't get to work on it there, but I got my own computer in 1991 and started exploring what I could do with it. In those days I was using CorelDraw 2 (CorelDraw's first release was in 1989). The tools available for digital art were simple and rough compared to what is available now. I took a blueprint home and did this elevation (building front) using flat, patterned, and simple gradient shapes. 15 years later I just retrieved it from my archives. Interestingly, after being run through different programs and saved many times, some of the colors had "faded" just like real paint or dyes would, and I restored the bright blue to the sky.
Nowadays almost all architectural renderings are done on high-end computers and the images are completely indistinguishable from photographs. In fact these images are "better" than photographs because the makers can build the image in ultra-detailed 3-D visualizations leading to a slightly disturbing inhuman perfection.
Ryan Homes house front, CorelDraw 2 on a PC, 1991.