Some walls I built still stand in Texas, walls to keep floodwaters under control, fireplaces for heating houses, columns to support roofs, foundations for a public school. They exist because they have a useful purpose. Some rock structures were built to satisfy a property owner’s concept of beauty. One of many cut-stone fenceposts in a decorative fence around a mansion now supports a mailbox. Other things I built were torn away decades ago.
As part of a scientist exchange program with China, I was one of the first Americans in decades to visit China’s Great Wall. I visited it with some of China’s best scientists.