Counting voussoirs

Voussoirs are the wedge-shaped stones that make up an arch. Counting them is a harmless habit and a good excuse to stand still on a bridge.

The odd number is not superstition. An arch wants a single keystone at the crown, so the count on either side is the same and the total is odd. When you find an even count, look closer: there is usually a repair, or the builder cut the crown in two.