CIU may refer to:
Ciudad Juárez (Spanish pronunciation: [sjuˈðað ˈxwaɾes], /ˈhwɑːrɛz/ WHAH-rez; Juarez City) is the largest city in the Mexican state of Chihuahua.
Ciudad Obregon (Spanish pronunciation: [sjuˈðað oβɾeˈɣon]) is the second largest city in the northern Mexican state of Sonora and named for Sonoran revolutionary general and president of Mexico, Álvaro Obregón.
Ciudad Nezahualcóyotl (Spanish pronunciation: [sjuˈðað nesawalˈkoʝotɬ]), or more commonly Ciudad Neza, is a city and municipality of State of Mexico adjacent to the northeast corner of Mexico City: it is thus part of the Mexico City Metropolitan Area.
Ciudad Real is one of the 52 constituencies (Spanish: circunscripciones) represented in the Congress of Deputies—the lower chamber of the Spanish parliament, the Cortes Generales—.
Ciudad Bolívar (Spanish pronunciation: [sjuˈðað βoˈliβar]; Spanish for "Bolivar City"), formerly known as Angostura, is the capital of Venezuela's southeastern Bolívar State.
La Ciudad de las Ideas (CDI) is a conference created by Andrés Roemer, to empower citizens and present innovative ideas in science, technology, art, design, politics, education, culture, business, entertainment and other areas of knowledge.
Ciudad Victoria (Spanish pronunciation: [sjuˈðad bikˈtoɾja]), is the capital city of the Mexican state of
Ciudad del Este (Spanish pronunciation: [sjuˈðað ðel ˈeste], Spanish for City of the East) initialed CDE is the second largest city in Paraguay and capital of the Alto Paraná Department, situated on the Paraná River.
Ciudad Acuña, also known simply as Acuña, (originally Garza Galán, later Villa Acuña) is a city located in the Mexican state of Coahuila, at 29°19′27″N 100°55′54″W and a mean height above sea level of 271 meters.