In 1921 a team of University of Chicago researchers, led by editor in charge Daniel D. Luckenbill, began transferring information from excavated clay tablets, unearthed in what is now Iraq, onto five-by-eight index cards. The cards, serving as the University's data set, were reproduced with a hectograph, a hand-operated ancestor of the modern photocopier.

For the first three-plus decades of the Chicago Assyrian Dictionary project, this is how it went. Information was gathered, either from existing tablets housed in museums or from new excavations in the former Mesopotamia, then transferred onto cards at the Oriental Institute. In cataloging the 5,000-year-old Akkadian language, researchers created a comprehensive cultural encyclopedia of early human civilization.

By the early 1950s the project's editorial board surveyed the growing collection of note cards, numbering more than a million, and agreed that, although data-collection would continue, it was time to begin producing volumes of the dictionary. "There is a little bit of paralysis that sets in when you have such a huge project," says Martha T. Roth, dean of humanities and current editor in charge of the Chicago Assyrian Dictionary. "In the early part of the 20th century, when the project was in the initial phases, I suspect people were reluctant to publish something, thinking more is coming. There came a point when a new team of editors said, ‘Let's just cut the Gordian knot.'"

The first volume, the letter H (Het), rolled off the press in 1956. The 21st and last volume, U/W, was printed late last year, almost 90 years after the undertaking began. All the volumes also are available online. On June 6 the Oriental Institute hosted a conference to celebrate the epic achievement.

Over the past half century, professor emeritus Robert Biggs helped to steer the dictionary to completion. Biggs, who joined the faculty in 1963 and retired in 2004, retains a third-floor office at the OI. "We can reconstruct, in tremendous detail, what went on in a household almost day by day," says Biggs, who specializes in the medical texts and practices of ancient Mesopotamian culture. The early writing was impressed into soft clay tablets, which were hardened either by the sun or through a baking process.

Although the ancient Mesopotamian records began about 1,000 years before those from ancient Greece and more than 2,000 years before ancient Rome, the preservation process has helped aspects of the culture endure in ways that the other cultures have not. The key distinction is that other ancient cultures wrote on papyrus or parchment, which has disintegrated through the millennia.

"We know more about ordinary people there," Biggs says, "than we know about ordinary people who lived in our own country in the 1700s."