The view looking up at the ceiling of a modernistic, brutal-ish cathedral on a hill overlooking downtown San Francisco. The cathedral was completed in 1970, same error as the Sydney Opera House. Era, not error. Sorry. My biases are showing.
Anyway, high overhead, the four giant sculpted concrete forms of the cathedral come together and, at their intersection, there are gaps -- channels where stained glass skylights form a giant red yellow and blue cross.
It really is a marvel of engineering: massive forms delicately held together by seams of glass.