to fulfill one of humanity's most audacious goals:

to collect all the knowledge in the world under one roof.

In its prime,

the Library of Alexandria housed an unprecedented number of scrolls

and attracted some of the Greek world's greatest minds.

But by the end of the 5th century C.E., the great library had vanished.

Many believed it was destroyed in a catastrophic fire.

The truth of the library's rise and fall is much more complex.

The idea for the library came from Alexander the Great.

After establishing himself as a conqueror,

the former student of Aristotle turned his attention

to building an empire of knowledge headquartered in his namesake city.

He died before construction began,

but his successor, Ptolemy I, executed Alexander's plans for a museum and library.

Located in the royal district of the city,

the Library of Alexandria may have been built with grand Hellenistic columns,

native Egyptian influences or a unique blend of the two.

There are no surviving accounts of its architecture.

We do know it had lecture halls, classrooms, and, of course, shelves.

As soon as the building was complete,

Ptolemy I began to fill it with primarily Greek and Egyptian scrolls.

He invited scholars to live and study in Alexandria at his expense.

The library grew as they contributed their own manuscripts,

but the rulers of Alexandria still wanted a copy of every book in the world.

Luckily, Alexandria was a hub for ships traveling through the Mediterranean.

Ptolemy III instituted a policy requiring any ship that docked in Alexandria

to turn over its books for copying.

Once the Library's scribes had duplicated the texts,

they kept the originals and sent the copies back to the ships.

Hired book hunters also scoured the Mediterranean in search of new texts,

and the rulers of Alexandria attempted to quash rivals

by ending all exports of the Egyptian papyrus used to make scrolls.

These efforts brought hundreds of thousands of books to Alexandria.

As the library grew, it became possible to find information on more subjects than ever before,

but also much more difficult to find information on any specific subject.

Luckily, a scholar named Callimachus of Cyrene set to work on a solution,

creating the pinakes, a 120-volume catalog of the library's contents, the first of its kind.

Using the pinakes, others were able to navigate the Library's swelling collection.

They made some astounding discoveries.

1,600 years before Columbus set sail,

Eratosthenes not only realized the earth was round,

but calculated its circumference and diameter

within a few miles of their actual size.

Heron of Alexandria created the world's first steam engine

over a thousand years before it was finally reinvented during the Industrial Revolution.

For about 300 years after its founding in 283 B.C.E., the library thrived.

But then, in 48 B.C.E., Julius Caesar laid siege to Alexandria

and set the ships in the harbor on fire.

For years, scholars believed the library burned as the blaze spread into the city.

It's possible the fire destroyed part of the sprawling collection,

but we know from ancient writings that

scholars continued to visit the library for centuries after the siege.

Ultimately, the library slowly disappeared as the city changed from

Greek to Roman, Christian, and eventually Muslim hands.

Each new set of rulers viewed its contents as a threat rather than a source of pride.

In 415 C.E., the Christian rulers even had a mathematician named Hypatia

murdered for studying the library's ancient Greek texts,

which they viewed as blasphemous.

Though the Library of Alexandria and its countless texts are long gone,

we're still grappling with the best ways to collect, access, and preserve our knowledge.

There's more information available today and more advanced technology to preserve it,

though we can't know for sure that our digital archives

will be more resistant to destruction than Alexandria's ink and paper scrolls.

And even if our reservoirs of knowledge are physically secure,

they will still have to resist the more insidious forces that tore the library apart:

fear of knowledge and the arrogant belief that the past is obsolete.

The difference is that, this time, we know what to prepare for.