A "Data Centre" can be anything from a server in someone's back bedroom to a proper enterprise class outfit, its just a name really but yes its basically a place where you put servers.
Proper data centre's though will have multiple power providers, backup generators, multiple internet providers, proper fire protection etc.
How they are setup is really a matter for each company/person as its down to personal choice basically its loads of cables everywhere :-) You may find this
link helpful. Ours is a
tier 3/4 DC
jen