A DC is really rather boring !

Racks of servers & comms equipment with a bit of power & network distribution.

Connections to your desired telco(s), hopefully a bit of rudundant routing between major points of failure within the DC itself. Ideally a couple of independantly run connections from your telco frames to their local hub (no point in having 2 fibres if they are in the same ducts when they put a JCB through the duct)

Power would ideally come from 2 or more independantly routed suppliers (again in seperate ducts) backed up by an on-site generator with a few days fuel on board AND a fuel contract :-)

Fire protection systems, air conditioners, access control systems, CCTV.

A few staff in house to manage reboots and watch cable TV (Oops... I mean monitor the comms & server status) and answer the hot-line.

Quantity & quality of the above will vary from DC to DC.

Don't forget the big sign on the outside so that everyone knows there's shed loads of servers sitting in the building. OK maybe this one's not such a good idea :-)