Old tenement buildings <i>do not</i> disappear, at least not in the Mission:
<a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11092556" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11092556</a>