I’m curious how one goes about getting their advertisement on a billboard. Specifically, what is the breakdown of parties involved in the process (i.e. how did the various spaces become billboards, can anyone just hang a giant sign on their building? Who rents what from whom? Do companies like Viacom or Titan Outdoor lease the space from the property owners?).
Around here, billboard companies look out for good sites (prominent streetcorners etc) and approach property owners. Sometimes, property owners approach them.
If the billboard company and property owner can reach an agreement in principle, at least in my location the next major hurdle is local ordinances governing outdoor advertising which are tight. The billboard company will take an option to lease or very occasionally buy the location and then use experience and professional town planners and lobbyists to try to get the council to agree to the billboard.
If the council agrees, the billboard company takes the lease/purchase and builds the billboard. They then lease that out to companies that want to advertise.
Apparently there can be a fair amount of contention about the municipal regulations governmening particular signs. There is a particularly loud series of quibbles over the database at Illegal Signs.ca, a new site that has found hunreds of billboards that blatently disregard the municipal rules.