Highly skilled masonry was evident all over the Sao Miguel, from paddock walls to old industrial buildings. The streets and sidewalks in Ponta Delgada had individual signature patterns made with highly contrasting black and white cobble stones. The black stone is basalt - local volcanic rock, but I don't know what the white coloured stone is.
There was an interesting tapered plaza at the City Hall with a statue of St. Michael the archangel. He appeared to be holding an umbrella rather than a sword, but maybe that's just because it was threatening rain that morning.
As a variation on the black and white, I noticed that the shallow water of the fountain made the white stones appear a blue.