The Golden Acre underground shopping mall in Cape Town used to be awesome. These days it's a little run down, a little dirty, and not a place that I'd rush to hang out at for an afternoon.
I used to work in the city a few years ago, and at that time I appreciated it greatly - not for the stores, but for the underground walkways. They offered a way to avoid having to wait for traffic lights to cross busy roads, and also provided shelter from the rain for much of the 10 minute walk between the train station and our office building.