Not necessarily doubting you, but it seems weird to do it that way if they’re building the second tower. At 121m, you’d need a raft slab or some significant piles, and it’d certainly need to be lower than the height of those forms. Why pour the at grade slab without excavating underneath? It’s common for top-down construction, but that's never been done here. Also look at the location of the site office along 5th, it would be basically under the second tower. Whatever is going on, it’s interesting.