Rog Phillips 
The Old Martians [EPUB ebook] 

They opened the ruins to tourists at a dollar a head but they reckoned without The OLD MARTIANS.
The man with the pith helmet had his back toward me. Hunched forward, he was screaming at the girl in the lens of his camera. “Don’t just stand there, Dotty! Move! Do something! Back up toward that column with inscriptions on it….”