Maps represent a high form of visual information. Here's a great example:
The 1854 Broad Street cholera outbreak was a severe outbreak of cholera that occurred near Broad Street (now renamed Broadwick Street) in Soho district of London, England in 1854. This outbreak is best known for the fact that John Snow discovered that cholera was spread by contaminated water....Snow later used a spot map to illustrate how cases of cholera were centred around the pump. SOURCE