In addition to /u/sunagainstgold's suggestion, I highly recommend that you read Alexandria and Alexandrianism by Kenneth Hamma. Alexandria and Alexandrianism focuses on the culture and history of the city from its foundation until Late Antiquity (early Middle Ages) and can be found online in its entirety on Google Books or Getty Virtual Library. The book has 19 fascinating essays on different facets of what made Alexandria from some of the foremost scholars in that area but it is also a fairly accessible read to a reader without much background info.

Having said that, it is hard to learn about the city of Alexandria without knowing much about the country it was a part of, and in that respect I recommend you check out Michel Chauveau's Egypt in the Age of Cleopatra, which of course looks fairly closely at Alexandria.

As an aside, I am not entirely sure what you mean by Alexandria's destruction. The city has certainly seen plenty of warfare and riots, and the receding coastline has submerged parts over the millennia, but it was never destroyed. In fact, it is still one of the most vibrant cities in Egypt and an important economic centre.

Edward Watts' intellectual biography of Hypatia--Hypatia: The Life and Legend of an Ancient Philosopher--goes deep into Alexandria as a physical place and as an intellectual culture in late antiquity. I know absolutely nothing about the topic going in, and found the discussion clear and readable.

(If you're interested in this kind of thing, Watts even does a good job explaining the philosophical currents of the time.)

Maybe /u/cleopatra_philopater has some other/better ideas?