US Flags, name of every Military person KIA and Service dogs, LEO, EMT’s and Fire. What better way to honor America and our Heroes. Scenes of beautiful places in the USA would be nice to, that is a lot of wall to cover. Past and present history including 9/11. First walk on the moon. Many things could be engraved on it. America’s finest moments and people.
You raise a good point. Advertizing could be sold to fund the wall. The downside is only a few select places would be valuable enough.