It's one you can't cut costs on, as everything has to run smooth, just a bare building DC needs everything from backup/uninteruptable power to multiple engineer skill staff, then facilities management for all the co-ordination of the climate and other issues including health and safety. If you plan secure server locations then possibly the building will have to be EMR shielded with wire mesh and non laser intrusive glass on the windows.

It's an artform in itself, and all that without even getting to the tech side