Build Up, or Tear Down?

I used to live in an older community, by the water, (ironically, just a few streets over from Bill Faloon's house). While the small, older, original homes were unimpressive, the property they sat on was very valuable. A lot of the residents wanted larger, more modern homes, so there was always a lot of construction going on. Whenever I would see a contractor's signs in one of my neighbor's yards, I would ask, "Building up, or tearing down?"

Sometimes, a contractor would be able to update the original home, and add a second story. However, some of the foundations simply could not support the larger, more valuable, more attractive, more functional structure, so the original home would have to be demolished. Makes me think of Alcor. What is there to build on?