Over the past quarter century, a dream has slowly been taking shape on the edge of the Mediterranean in the fabled but faded Egyptian city of Alexandria. This autumn, the world will finally get a chance to take the measure of that dream.

Two millennia ago, the library at Alexandria was the focal point of the known intellectual universe. Housing hundreds of thousands of papyrus scrolls, it was a beacon for scholars rivaling the nearby lighthouse of Pharos as a wonder of the ancient world. Its destruction -- begun during the Roman invasion of 48 B.C. and completed several hundred years later at the hands of Christians -- became a byword for vandalism, overshadowing such modern cultural crimes as the Nazis' book burnings or the razing of a pair of centuries-old Buddhas in Afghanistan last March. Every schoolchild knew its sad story.

Then, 25 years ago, an Alexandria history professor came up with the idea of reviving the legendary library on or near the site of the original. With the support of UNESCO, the Egyptian government and a number of foreign countries, including Japan, the enormously ambitious project went forward. In October, barring any further delays, the brand-new, state-of-the-art Bibliotheca Alexandrina will at last gets its partial public opening, and a full-scale inauguration is scheduled for next spring.

There is much riding on the opening -- for Alexandria, for Egypt, for the Middle East, and for the entire world of learning. The city, now a down-at-heel ghost of its former illustrious self, hopes the new facility will jump-start its economic and cultural revival. The government hopes the library will again become what its chief patron, Egyptian First Lady Suzanne Mubarak, calls "a lighthouse for thought," putting Egypt back on the intellectual world map. Others have even grander visions: Egyptian media have dubbed the Bibliotheca "the fourth pyramid" in anticipation of a lucrative tourist spinoff, and the facility's new director general talks of Alexandria as a kind of future Davos -- a hub of technical research in the same way the Swiss town is now a hub of economic debate. Meanwhile, the Arab world anticipates new respect for the region (with a projected 8 million books, the Bibliotheca will be the biggest in the Middle East) and scholars and researchers worldwide are eager to test its claims as the library of the digital future.

There is no questioning the dramatic symbolism or beauty of the Norwegian-designed building, as memorable in its way as those other great contemporary architectural landmarks, the Sydney Opera House and the Guggenheim Museum in Bilbao, Spain. A cut-off cylinder, it hovers at the sea's edge like a half-risen sun. The flat, tilted roof facing the Mediterranean mimics the gridlike design of a microchip, while its circular granite walls are etched with characters from all the world's notation systems, from hieroglyphs on -- no words, just the building blocks of words, music and mathematics. Thus, the building embodies its mission: Stone meets anodized aluminum, primitive past meets high-tech future, the old informs the new.

But a library needs more than fancy architecture, as the designers of Paris' handsome but dysfunctional Bibliotheque nationale have learned to their chagrin. It also needs to live up to exacting standards of performance. In this respect, although the Bibliotheca boasts the world's biggest reading room and a dazzling array of other facilities, including auditoriums, a conference center, museums and a planetarium, the jury is still out. Some critics even predict "a world-class fiasco." They cite, among other things, an inadequately funded and unfocused acquisitions program and a lack of convincing assurances that this "leading digital facility" will not become a warehouse for obsolete computer systems. Remember Shelley's Ozymandias? A white elephant on the scale of the Bibliotheca could end up a colossal wreck in the desert a lot faster than the monuments of that doomed king -- or the first, truly great library of Alexandria.

Then again, every ambitious project has its detractors. Bibliotheca officials acknowledge the criticisms but say they have been addressed. Collection planning has been focused, fields of specialization have been chosen, a distinguished international board of trustees is in place. The library can only be judged over time -- at least a decade, according to its recently appointed director. Considering Egypt's elongated history, perhaps the director is better attuned to the exigencies of time than are some of his New World critics.

In the meantime, the library's initial opening this fall will be a red-letter event for scholars everywhere. Certainly, such a splendid idea deserves to succeed. Let's give the Bibliotheca Alexandrina its decade before we decide whether it was only a dream.