Previously in poorly-thought-out desert arcologies:
I once spent four days in the Kingdom. Notable observations from that regrettable gambit: 1. Literally nobody works (except the slaves). 2. They don't let Westerners (maybe all foreigners...don't know) wander the streets of Riyadh alone. Not sure if this is to protect them or us. Probably both. 3. A boring-ass country with no culture or entertainment to speak of is not made less boring by the lack of alcohol, nor by the fact that Saudi Airlines blurs out women's legs in the in-flight movies. 4. 113ยบ Heat SUCKS and I wouldn't want to take a 5 minute walk from anywhere to anywhere, no matter how conveniently located my local halal butchery is. 5. After I gave my talk to the conference I was attending, a young medical student approached me to say how happy he was to meet a real American scientist. We chatted for a minute or two, and I gave him my card. Not 30 minutes later he sent me a long email about how hard it is there, and that he had expressed a disbelief in God, for which he was punished with beatings from the religious police. It felt weirdly like a trap, so I just responded with something anodyne. But true or not true, the email is problematic either way. 6. When I tried to get my visa, I naturally visited the embassy's website, and it's one of those sites where Chrome throws up a big red screen saying GO BACK TO SAFETY YOU DUMB MOTHERFUCKER!!! I could go on, but my point is that I think that the Kingdom and His Highness have some more pressing problems than urban planning if they want to attract foreign investment that doesn't involve resource extraction.
From the designer of the 3,000 square foot house that was 300 feet long and 10 feet wide comes a newer and even poorer design.
I love arcologies. I own a first edition of this. I have maybe five books on earth-sheltered habitat, which always come down to some form of arcology because you're much better off building the whole damn thing underground. Unfortunately, arcologies generally fly in the face of "the city is there because it's a natural place for a city to be" in favor of "the city is there because it stands as a testament to our own hubris." Historically, humans live on top of each other without a whole lot of difficulty. The Sumerians and Babylonians were basically communist and their collectively occupied cities lasted three or four thousand years. Feudalists and market capitalists suck at living on top of each other.