Bagno di massa in piscina a Chongqing, Cina

In this Sunday, Oct. 30, 2011 photo, tourists crowd a hot spring pool in southwestern China’s Chongqing city. Countries around the world marked the world’s population reaching 7 billion Monday, Oct. 31 with lavish ceremonies for newborn infants symbolizing the milestone and warnings that there may be too many humans for the planet’s resources. While demographers are unsure exactly when the world’s population will reach the 7 billion mark, the U.N. is using Monday to symbolically mark the day. (AP Photo)