Thomas Telford built nearly 1000 bridges in the first part of the 19th century.

If this one is indicative, what a work he accomplished!

The scenery here was wonderful, as usual, and there was even another surprise in the little house on the side of the stream (in the last image).

The use of the arch is pervasive in Scotland. It allows gravity to support the structure. In the US, we would rather force our structures up with steel. (It costs more.)