Even before there were bound books, there were libraries. In cities across the world, these temples of knowledge served not only as storehouses for clay tablets and scrolls, but also as centers of culture and learning. Below, get the facts on eight of the most magnificent libraries of the ancient world.

The Library of Ashurbanipal

The world's oldest known library was founded sometime in the 7th century B.C. for the "royal contemplation" of the Assyrian ruler Ashurbanipal. Located in Nineveh in modern day Iraq, the site included a trove of some 30,000 cuneiform tablets organized according to subject matter. Most of its titles were archival documents, religious incantations and scholarly texts, but it also housed several works of literature including the 4,000-year-old "Epic of Gilgamesh." The book-loving Ashurbanipal compiled much of his library by looting works from Babylonia and the other territories he conquered. Archaeologists later stumbled upon its ruins in the mid-19th century, and the majority of its contents are now kept in the British Museum in London. Interestingly, even though Ashurbanipal acquired many of his tablets through plunder, he seems to have been particularly worried about theft. An inscription in one of the texts warns that if anyone steals its tablets, the gods will "cast him down" and "erase his name, his seed, in the land."

The Library of Alexandria

Following Alexander the Great's death in 323 B.C., control of Egypt fell to his former general Ptolemy I Soter, who sought to establish a center of learning in the city of Alexandria. The result was the Library of Alexandria, which eventually became the intellectual jewel of the ancient world. Little is known about the site's physical layout, but at its peak it may have included over 500,000 papyrus scrolls containing works of literature and texts on history, law, mathematics and science. The library and its associated research institute attracted scholars from around the Mediterranean, many of whom lived on site and drew government stipends while they conducted research and copied its contents. At different times, the likes of Strabo, Euclid and Archimedes were among the academics on site.

The great library's demise is traditionally dated to 48 B.C., when it supposedly burned after Julius Caesar accidentally set fire to Alexandria's harbor during a battle against the Egyptian ruler Ptolemy XIII. But while the blaze may have damaged the library, most historians now believe that it continued to exist in some form for several more centuries. Some scholars argue that it finally met its end in 270 A.D. during the reign of the Roman emperor Aurelian, while others believe that it came even later during the fourth century.

The Library of Pergamum

Constructed in the third century B.C. by members of the Attalid dynasty, the Library of Pergamum, located in what is now Turkey, was once home to a treasure-trove of some 200,000 scrolls. It was housed in a temple complex devoted to Athena, the Greek goddess of wisdom, and is believed to have comprised four rooms--three for the library's contents and another that served as a meeting space for banquets and academic conferences. According to the ancient chronicler Pliny the Elder, the Library of Pergamum eventually became so famous that it was considered to be in "keen competition" with the Library of Alexandria. Both sites sought to amass the most complete collections of texts, and they developed rival schools of thought and criticism. There is even a legend that Egypt's Ptolemaic dynasty halted shipments of papyrus to Pergamum in the hope of slowing its growth. As a result, the city may have later become a leading production center for parchment paper.

The Villa of the Papyri

While it wasn't largest library of antiquity, the so-called "Villa of the Papyri" is the only one whose collection has survived to the present day. Its roughly 1,800 scrolls were located in the Roman city of Herculaneum in a villa that was most likely built by Julius Caesar's father-in-law, Lucius Calpurnius Piso Caesoninus. When nearby Mount Vesuvius erupted in 79 A.D., the library was buried--and exquisitely preserved--under a 90-foot layer of volcanic material. Its blackened, carbonized scrolls weren't rediscovered until the 18th century, and modern researchers have since used everything from multispectral imaging to x-rays to try to read them. Much of the catalogue has yet to be deciphered, but studies have already revealed that the library contains several texts by an Epicurean philosopher and poet named Philodemus.

The Libraries of Trajan's Forum

Sometime around 112 A.D., the Emperor Trajan completed construction on a sprawling, multi-use building complex in the heart of the city of Rome. This Forum boasted plazas, markets and religious temples, but it also included one of the Roman Empire's most famous libraries. The site was technically two separate structures--one for works in Latin, and one for works in Greek. The rooms sat on opposite sides of a portico that housed Trajan's Column, a large monument built to honor the Emperor's military successes. Both sections were elegantly crafted from concrete, marble and granite, and they included large central reading chambers and two levels of bookshelf-lined alcoves containing an estimated 20,000 scrolls. Historians are unsure of when Trajan's dual library ceased to exist, but it was still being mentioned in writing as late as the fifth century A.D., which suggests that it stood for at least 300 years.

The Library of Celsus

There were over two-dozen major libraries in the city of Rome during the imperial era, but the capital wasn't the only place that housed dazzling collections of literature. Sometime around 120 A.D., the son of the Roman consul Tiberius Julius Celsus Polemaeanus completed a memorial library to his father in the city of Ephesus (modern day Turkey). The building's ornate façade still stands today and features a marble stairway and columns as well as four statues representing Wisdom, Virtue, Intelligence and Knowledge. Its interior, meanwhile, consisted of a rectangular chamber and a series of small niches containing bookcases. The library may have held some 12,000 scrolls, but it most striking feature was no doubt Celsus himself, who was buried inside in an ornamental sarcophagus.

The Imperial Library of Constantinople

Long after the Western Roman Empire had gone into decline, classical Greek and Roman thought continued to flourish in Constantinople, the capital of the Byzantine Empire. The city's Imperial Library first came into existence in the fourth century A.D. under Constantine the Great, but it remained relatively small until the fifth century, when its collection grew to a staggering 120,000 scrolls and codices. The size of the Imperial Library continued to wax and wane for the next several centuries due to neglect and frequent fires, and it later suffered a devastating blow after a Crusader army sacked Constantinople in 1204. Nevertheless, its scribes and scholars are now credited with preserving countless pieces of ancient Greek and Roman literature by making parchment copies of deteriorating papyrus scrolls.

The House of Wisdom

The Iraqi city of Baghdad was once one of the world's centers of learning and culture, and perhaps no institution was more integral to its development that the House of Wisdom. First established in the early ninth century A.D. during the reign of the Abbasids, the site was centered around an enormous library stocked with Persian, Indian and Greek manuscripts on mathematics, astronomy, science, medicine and philosophy. The books served as a natural draw for the Middle East's top scholars, who flocked to the House of Wisdom to study its texts and translate them into Arabic. Their ranks included the mathematician al-Khawarizmi, one of the fathers of algebra, as well as the polymath thinker al-Kindi, often called "the Philosopher of the Arabs." The House of Wisdom stood as the Islamic world's intellectual nerve center for several hundred years, but it later met a grisly end in 1258, when the Mongols sacked Baghdad. According to legend, so many books were tossed into the River Tigris that its waters turned black from ink.