Shooter was on roof of AGR Building. It appears the Stage was setup near the Concession Road area near where you see 3 buildings in a row. The guy who saw he shooter was from the Brenckles Greenhouse who had walk up to the field just to hear the rally speech.
Map of area..
Late in the ‘16 campaign Trump had to give up going into any large American city for a rally because of democrat violence. He started flying into these venues so he and his supporters were safe from the democrat goons. You can’t escape them.