code:

planet_event = {
	id = urbanization.100
	title = "urbanization.100.name"
	desc = "urbanization.100.desc"
	picture = GFX_evt_urban
	#show_sound = **unfinished**
	location = ROOT

	is_triggered_only = yes

	option = {
		name = urbanization.100.a
		change_pc = pc_urban
		add_modifier = {
			modifier = "pm_urban_world"
			days = -1
		}
		

		hidden_effect = {
			random_tile = {
				limit = {
					has_building = "building_urbanization"
				}
				remove_building = yes
			}
			remove_modifier = "pm_urbanization_project"
		}
	}
}