I want to get a prime lenses. But I'm not sure which to get. I want something that can do portrait, urban shooting (buildings and such), museums, and some landscape. I'm thinking the 85mm Nikon might do the trick. Thoughts?
Head and shoulders portrait suggest mild (2x) telephoto (but full length portrait needs wide angle). Museum maybe needs intermediate (depends on what). Landscapes probably wide angle (again, depends on what). You may need more than one.

Back in the day, before zooms (except maybe a few in Hollywood), we carried an arsenal of various prime lenses.
I don't mean to be a spoilsport, but that day is gone now, and a zoom does come to mind, ready for anything.

The zoom won't do f/1.8, but f/1.8 is only a small niche of the overall uses, and normally impractical.