The renowned Spanish painter and sculptor, Antonio López, is responsible for this bronze sculpture set  consisting of two  giant baby heads, one with its eyes open and the other with its eyes closed, located outside the AVE arrivals terminal at Atocha station. 

To mark the remodelling works of the station, the Ministry for Public Works commissioned this project to the artist in 2002, which influenced by the subsequent terrorist attacks on 11 March 2004, represents a memorial to the victims.   The sculpture was originally erected in the arrivals hall at Puerta de Atocha station in 2008, and was later moved to its current location in 2010.  

Day and Night is the first monumental sculptural work by Antonio López which is on display in a public place.  It portrays his granddaughter, Carmen, when she was six months old, through two heads of the same size, which represent two different moments,  wakefulness and sleep. The author wishes to convey the idea of the passage of time accompanied by the passing of trains.