A bridge is an unappreciated marvel of engineering. Life as we know it would not be possible without them. Even a small bridge across a stream, if it was destroyed by a flood, would cause major disruptions to society. But bridges are costly in terms of resources needed to design, build, and maintain them. It's easy to miss a structural bridge when driving over it. There are probably more bridges out there than you realize. But there were no concrete bridges in Banff 200 years ago. Now Banff couldn't really exist without them.