Pompey's Pillar is a unique site that used to be a large structure with baths and channels used for washing and also measuring the level of the Nile. The site is in ruins now, but there are some interesting sphinxes and a pillar remains standing. There are also a few underground libraries at the site that are interesting.
The site is not in a good area of town by any means. Alexandria itself was very dirty when we visited and there was mountains of trash and rubble littering the streets. I'm 90% sure I hears some very nearby gun shots when we were at the sites, and our tour guide became extremely nervous at the sounds but pretended like it was nothing. The site is confined by large walls so it is safe, but the outside looks a little sketchy.
If you're in Alexandria, take a trip there. We did a day trip from Cairo; however, and for the cost I did not find Alexandria worth the trip.
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