A large number of cloud providers will likely have a blend of their own datacenters as well as installations within other providers' centers. I've been in that

A large number of cloud providers will likely have a blend of their own datacenters as well as installations within other providers' centers. I've been in that data center at 200 Paul Ave in San Francisco, back in early 2010, and can confirm that at the time, it definitely had multiple floors' worth of racked, running equipment owned by Facebook, despite them already having their own data centers at that point.