a perfect spot for a city couldn't be built upon. it had an ancient tower on it and the setter couldn't found a city on the location or destroy the tower through pillaging. there were no other obsiticals, such as being in anothers culture or too close to another city. so i'm fairly certain it was the tower. as the title says, an annoyance, not really a bug i think. im sure another unit could have destroyed it for the setter (comp crash with no save before i could try) but this would delay the building of the city. edit: i take that back, i guess you can't wipe towers at all since .25, however, you can wipe out castles and citadels via improvements or pillaging, so if you wait for an ancient tower to grow, you can wipe it. significantly more annoying.