The Domesday Book details the lands and resources that belonged to King William the Conqueror in 1086, proving an indispensible record of the wealth of England and what daily life was like at the time.
With an English translation of the book's Latin inscriptions online, visitors will now be able to search a place name, see the index entry made for the town, city or village and for fee of about six dollars download the appropriate page.
"Everyone can now enter The National Archives' website, discover how and why Domesday was made and read about its enormous importance in history," said Adrian Ailes, Domesday expert at the National Archives.
The ancient document is thought to have been called "Domesday" - a reference to the biblical day of judgment or "doomsday" - because there could be no appeal against the census takers' rulings.
The book was commissioned in 1085, when England was threatened with invasion from Denmark and only a few years after William defeated King Harold at the Battle of Hastings in 1066 to take England's throne.
To pay for a mercenary army, William needed to know what financial and military resources were available to him, therefore he sent assessors to more than 13,000 places across the country.
The book was voted the nation's finest treasure in 2005, yet the National Archive which keeps it says that less than one percent of the population has seen the original.