Recycling Communications Towers

The question today is what happens to the many, many Communications Towers that adorn our landscape at this time when the technology for communications becomes even more advanced that what we enjoy today. What will happen to these Towers when they are no longer needed. I am sure that the land owners where these towers are constructed are receiving a rental fee, which they should. That stated, are there rules and regulations on the books on a national basis that requires that unused towers be dismantled and recycled? The Flower Child would like to know. If any reader of this blog has an answer, please leave a comment here.