A reader examines a page from the Codex Sinaiticus, the earliest surviving Bible. Pages and fragments gathered from four separate locations have been reunited online. (The British Library/Associated Press)

An online project by the British Library has reassembled the surviving pages of the world's oldest Bible.

The Codex Sinaiticus, written by Greek scholars in the fourth century, exists in four separate pieces in Britain, Germany, Russia and Egypt.

But all of the extant text of Codex Sinaiticus went online Monday, along with interpretations in modern Greek and in English, for those who cannot read the ancient language.

The book "offers a window into the development of early Christianity and first-hand evidence of how the text of the Bible was transmitted from generation to generation," said Scot McKendrick, head of Western manuscripts at the British Library.

Scholars continue to study the text, written about the time that Constantine was adopting Christianity as the religion of the Romans, to see how the Christian faith has evolved.

The pages, written on paper-thin parchment, include a complete New Testament, with early versions of the four Gospels, and about half of the Old Testament. The first part of what is now considered the Bible — from Genesis to 1 Chronicles — is missing.

Codex Sinaiticus, which loosely translated means "the book from Sinai," was discovered at the Monastery of Saint Catherine at Mount Sinai in Egypt by German Bible scholar Constantine Tischendorf in the mid-19th century.

Much of it wound up in the National Library of Russia in St. Petersburg, and the British Library bought 347 pages from Soviet authorities in 1933.

There are 43 pages at the University Library in Leipzig, Germany, and 12 more pages and 40 fragments were discovered in 1975 at the monastery at Mount Sinai.

"If you would have liked to see it before, you would have had to travel to four countries in two continents," said Juan Garces, manager of the project. "If you want to see the manuscript right now, all you have to do is go online and experience it for yourself."

The British Library organized the project to digitize the fragile original text and to pull together scholarly interpretation for online readers.

Interest in the site was so high the first day, the library was reporting users had to make multiple attempts to gain access.