Wandering through the University of Pennsylvania Museum is like taking a walk around the ancient world. Dark narrow passageways lined with Egyptian mummies flow into stately galleries of Etruscan art; smiling Buddhas contemplate rooms full of Mesopotamian pottery; and a pathway of colorful Roman mosaics vanishes into a forest of Native American totem poles.

It can take hours, even days, to make your way through the 21 exhibits that crowd the museum’s imposing three-story brick building in downtown Philadelphia (above). But the University Museum (more formally known as the University of Pennsylvania Museum of Archaeology and Anthropology) has not always operated on such a grand scale. When it was first established a century ago, the museum occupied only a single large room in the college library and featured one important exhibit: the ancient Sumerian artifacts recovered from the university’s 1888–1900 expedition to the ancient Mesopotamian city of Nippur. (The photo below shows these artifacts exhibited in the museum’s first Semitic Gallery, around 1900.)

For over three decades—until the university co-sponsored Leonard Woolley’s spectacular 1929 discovery of the “Royal Tombs of Ur”—the thousands of cuneiform tablets found by the Nippur expedition constituted the bulk of the museum’s collection. Today, the tablets are still one of the museum’s most important assets—though you might not suspect it from their humble appearance and modest accommodations.

Currently, the museum is undergoing major renovations to make way for a new climate-controlled storage wing, and most of its cuneiform tablets have been moved to an empty classroom in the building’s basement. To get to the “tablet room,” you descend two flights of stairs, thread your way through several exhibits and check in with two security guards. Eventually, if you don’t lose your way or get booted out, you come to a pair of locked brown doors with an old-fashioned cowbell dangling in front. There is nothing to indicate that you’ve arrived at your destination, just a handwritten sign that instructs you to “please ring the bell” for access.

Beyond these doors sit 3,000 years of ancient history crammed into a long, narrow room full of bookshelves, filing cabinets and steel specimen drawers. Everywhere you look there are of stacks of journals and piles of paper. An old-fashioned card catalogue, some mysterious cardboard boxes and a whimsical model ziggurat (complete with a modern skylight) also lie scattered around the chamber. Here, clearly, scholarship and research are prized above appearances.

The curator in charge of this cluttered domain is an eminent Assyriologist named Erle Leichty (the figure at left in the photo above). A soft-spoken, bespectacled 66-year-old man with pleasant even features, thinning gray hair and a fondness for navy blue ties, Leichty looks more like your high school chemistry teacher than an internationally recognized scholar. But his passion for all things cuneiform becomes obvious as soon as he starts talking about his work and his tablets.

“There are about 40,000 tablets,” Leichty told me during a recent tour of the tablet room. As he spoke, he gestured expansively at the rows of steel cabinets that surrounded us. “It’s probably slightly smaller than Yale’s [Babylonian collection], but it’s a little more important because our tablets were mostly excavated and so we know more or less where they came from.”

About 10,000 of the tablets in the room come from Ur, but the bulk of the collection still consists of finds from the scribal quarter at Nippur. The Nippur “library” includes Old Babylonian school texts (dating from around 1800 B.C.), as well as legal, economic and scientific documents from the mid-third millennium B.C. to the first century B.C. The most celebrated document in the collection, dating from around 2200 B.C., is the world’s oldest medical text. This drab, mud-colored tablet, which resembles a small scratched-up brick, is inscribed with a list of ancient Sumerian herbal remedies. Its image has been reproduced on everything from textbooks to pharmaceutical advertisements.

Scholars of the ancient Near East take a special interest in the museum’s collection of literary tablets, which account for more than 80 percent of the world’s known Sumerian literature. The museum’s collection includes a rare, 18th-century B.C. fragment of the Old Babylonian version of the Gilgamesh epic. This tablet, referred to as Gilgamesh P (or the Pennsylvania Tablet), corresponds to most of the second tablet of the 12-tablet version of the epic. Although much later copies of the entire epic have been found (including a number of seventh-century B.C. copies from Nineveh), the Pennsylvania tablet is one of only a handful of tablets from the Old Babylonian period—that is, from the time when older Sumerian stories about Gilgamesh were being put into one continuous narrative. Most of these older Sumerian tales can also be found in the University Museum. (They were first published by the celebrated Assyriologist Samuel Noah Kramer, during his tenure as curator of the tablet collection in the 1950s.)

As our visit to the tablet room drew to a close, Leichty reached into a drawer filled with hundreds of inscrutable clay fragments and plucked out Hermann Hilprecht’s notorious “flood tablet.” This cracked and broken-edged clay record, which dates to the early second millennium B.C., is badly damaged and its inscription is only partially legible. But the text clearly recounts the story of a mythic king named Ziusudra, who built a “huge boat” and “saved the seed of mankind” from a terrible storm sent by the gods.

Remarkably, however, these literary and historical works represent only the tip of the iceberg. Although the university’s tablet collection is the most heavily researched in the world, less than one-third of its contents have been deciphered and published to date. Many of the tablets have never even been formally catalogued or organized; instead, they have simply been numbered and stowed away in specimen drawers according to the order in which they came out of the boxes shipped from Nippur.

There are many reasons for the slow pace of cuneiform publications. Most of the tablets in the collection actually consist of hundreds, even thousands, of tiny clay fragments, some of them containing only a single line or character of text. It can take decades for a scholar to locate and reassemble all the pieces of the particular puzzle he is working on—if he is lucky enough to find them at all. In many cases, the inscriptions on the cuneiform tablets have also been partially eroded. (To prevent any further damage to the inscriptions, the museum staff has fired all 40,000 of the collection’s originally sun-baked tablets in a modern kiln, rendering them, Leichty said, “virtually indestructible.”)

According to Leichty, early pioneers like Hilprecht tried to reassemble and publish as many tablets as they could; but they were hampered by a lack of familiarity with cuneiform texts and their own elementary skills of decipherment. “From the standpoint of cuneiform studies, Hilprecht does not have a really great legacy,” Leichty said. Hilprecht’s real contribution was that he came first.

Today, thanks to the Herculean publishing efforts of post-World War II scholars like Kramer, there is a substantial corpus of cuneiform writings for scholars to draw on. There are also established lexicons and dictionaries. Yet only about 200 scholars in the world can sight-read Old Babylonian or Akkadian cuneiform inscriptions. And when tablets are badly damaged or belong to some previously unknown literary genre, even the most experienced decipherers struggle.

“There was a big prism here with Sumerian literature on it that was badly damaged,” Leichty recalled. “It was in bad shape, and my colleague [Curator Emeritus] Ake Sjoberg had that thing sitting on his desk for more than 15 years. I watched him. Every time he got bored, he picked it up again. He just kept coming back to it, and after about 15 years, he published it. I think he read most of it in the end.”

In today’s highly specialized academic environment, many scholars no longer try to publish large numbers of tablets. Instead, they focus on specific problems that require them to use only a small portion of the tablet collection. “We’re always having people come in to make new text editions of a particular Sumerian literary piece,” Leichty said. “That’s the most common research project and what people like most.”

The tablet collection is maintained and studied by a staff of three full-time university professors and one research fellow. Leichty himself is a specialist in first-millennium B.C. royal inscriptions. He spends most of his time deciphering the writings of Esarhaddon, king of Assyria from 680 to 669 B.C. But the main scholarly project underway here is the publication of a multivolume Sumerian dictionary—the first comprehensive list of all 15,000 known Sumerian words, along with their uses and contexts.

Assembling such a dictionary is a daunting task. Unlike Akkadian, a Semitic language related to modern Hebrew and Arabic that was used by both the Babylonians and the Assyrians, Sumerian is extinct and linguistically isolated. As a result, Assyriologists must deduce the meaning of each Sumerian word from its written context or from Akkadian translations of Sumerian documents and word lists. Sumerian writing is also non-alphabetic. Its wedge-shaped cuneiform signs are not letters, but logograms, or symbols that represent entire words or parts of words (syllables). Before scholars can compose an alphabetical dictionary, they must first determine how each of Sumerian’s 600 logograms was pronounced and then transliterate it into some alphabetic language (in this case, using the Latin alphabet). Right now, most Assyriologists agree that the basic phonetic inventory of Sumerian can be reproduced using four vowels and 13 consonants from the Latin alphabet, but there is still some debate about exactly how many sounds Sumerian actually used. In short, the Sumerian Dictionary Project is a massive undertaking—one that the museum staff has been working on since 1976. So far, they have completed only one volume (translitered words beginning with the Latin letter “A”) in a projected 17-volume series.

Leichty laughingly predicts that work on the dictionary, which is sponsored by the National Endowment for the Humanities, will continue well into the 21st century. It may take even longer if the project’s scholars can gain access to cuneiform tablets that are still being unearthed by archaeologists and scavengers. Experts estimate that somewhere between one and two million cuneiform tablets have already been excavated, and another 25,000 or so are found every year. More than 99 percent of these tablets have never been published.

Nevertheless, said Leichty, “We have more documentation for these 3000 years B.C. than for any other time in mankind’s history until the invention of the printing press.” His eyes came to rest for a moment on a drawer full of ancient writings. “This is one place where we are going to be able to continue to learn virtually forever.”