Step 1 is not necessarily the worst idea, but it depends on you hiring competent people and managers (and it sounds like everything that followed was a result of this failure.)
At least the initial hiring of consultants was done publicly. (Subcontracting is usually not done via public tender, since it is assumed that the main contractor's bid includes the complexity and cost of whatever subcontractors they might need, and requiring public tender for everything would slow things down significantly.)
The problem was that actually following the advice to keep minimal in-house staff who could check the work was really stupid, no matter who would win such tenders.
* All the public bids where too expensive. so the City decided to be it's own contractor, it must be cheaper.
* Keep changing plans, double the size .. after starting construction.
* Hire an architect that hates shops, change all plans again to add shops.
* Start paying contractors by time instead of by job, they start stealing.
* because of all the changes : stairs don't fit, cable management is broken, firesafety doesn't work.
* Don't fuck with german firesafety, they won't approve it, and you can't bribe them.
16 years later: opening with a capacity that is far below what's needed.