Though it didn't take 200 years, the Altare della Patria took 40 years to build from 1885 to 1935 and is quite grand and impressive: https://en.wikipedia.org/wiki/Altare_della_Patria .

It was actually my favorite structure in Rome when when I visited with the Pantheon in a close second.

I believe that it counts as an example of a long running and grandiose engineering project.