The Library of Congress maintains the online map collection Web site which contains maps from 500 years in seven different categories. The site, entitled Map Collections: 1500-1999, can be browsed by cities and towns, conservation and environment, discovery and exploration, general maps, transportation and communication, military battles and campaigns, and cultural landscapes. The database can be searched by keyword and also browsed by additional parameters that include geographic location, subject, creator, and title. Each map has a description, can be zoomed to fine detail, and even downloaded in most cases free of charge. A wonderful resource for anyone interested in maps or any of the subjects they portray.