The whole "we don't build beautiful things anymore" problem is a lot bigger than just building beautiful things.
Even if you manage to build, preserve, or restore a beautiful place -- it will be full of people with no self-respect, and the architecture of the corporate slop we're all addicted to will also take over.
People will mill around in their jammies, gulping great big cups of sugary coffee drinks, scrolling on their cell phones, and strung-out vagrants will mill around with impunity -- because we no longer live, dress, eat, make policy, or sit in public with even the barest trace of self-respect.
In essence, in order for beauty to exist in a public way, the dominant cultural mode has to be one of universal self-respect. Those who exhibit none must be reprimanded or removed from sight. And so far as cultural modes go, this one is notoriously hard to inculcate or enforce.
Once someone has degenerated at all, they become rabidly defensive, as if accused -- they vehemently defend their ghastly sweatpants, their Big Gulp cup of syrupy latte, their penchant for slack-jawed idling on TikTok in public. They are offended at the idea of enforcing basic social standards in public, because it would be "mean" to do so. The very defensiveness such people exhibit is the real obstacle to public beauty before anything else.
"Build beautiful buidlings again" at your own peril until this attitude is somehow erased from the cultural canon.