The addresses are just owned by a company (Google Inc.) located in Mountain View, according to WHOIS information from ARIN. But they are served from whichever location Google decides to announce a route to that range from.
For their DNS servers, Google is using anycast, and the same addresses can in fact be routed to several different locations:
On the Internet, anycast is usually implemented by using BGP to simultaneously announce the same destination IP address range from many different places on the Internet
This is the BGP entry for that route:
BGP routing table entry for 8.8.8.0/24, version 50533132
Paths: (18 available, best #12, table Default-IP-Routing-Table)
Not advertised to any peer
7018 15169, (received & used)
12.123.137.124 from 12.123.137.124 (12.123.137.124)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:37232
7018 15169, (received & used)
12.123.139.124 from 12.123.139.124 (12.123.139.124)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:34011
7018 15169, (received & used)
12.123.145.124 from 12.123.145.124 (12.123.145.124)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:33051
7018 15169, (received & used)
12.123.21.243 from 12.123.21.243 (12.123.21.243)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:39343
7018 15169, (received & used)
12.123.13.241 from 12.123.13.241 (12.123.13.241)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:32112
7018 15169, (received & used)
12.123.9.241 from 12.123.9.241 (12.123.9.241)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:38001
7018 15169, (received & used)
12.123.133.124 from 12.123.133.124 (12.123.133.124)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:36244
7018 15169, (received & used)
12.123.5.240 from 12.123.5.240 (12.123.5.240)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:34011
7018 15169, (received & used)
12.123.134.124 from 12.123.134.124 (12.123.134.124)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:36244
7018 15169, (received & used)
12.123.142.124 from 12.123.142.124 (12.123.142.124)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:33051
7018 15169, (received & used)
12.123.17.244 from 12.123.17.244 (12.123.17.244)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:36244
7018 15169, (received & used)
12.123.1.236 from 12.123.1.236 (12.123.1.236)
Origin IGP, localpref 100, valid, external, best
Community: 7018:2500 7018:37232
7018 15169, (received & used)
12.123.37.250 from 12.123.37.250 (12.123.37.250)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:36244
7018 15169, (received & used)
12.123.45.252 from 12.123.45.252 (12.123.45.252)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:32112
7018 15169, (received & used)
12.123.33.249 from 12.123.33.249 (12.123.33.249)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:39220
7018 15169, (received & used)
12.123.25.245 from 12.123.25.245 (12.123.25.245)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:34011
7018 15169, (received & used)
12.123.41.250 from 12.123.41.250 (12.123.41.250)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:37232
7018 15169, (received & used)
12.123.29.249 from 12.123.29.249 (12.123.29.249)
Origin IGP, localpref 100, valid, external
Community: 7018:2500 7018:33051
Best Answer
A quick comparison of Google Public DNS with OpenDNS (which has been around for a long time).
If you have to access sites banned by Google DNS (or, OpenDNS for that matter), you can skip these configurations when you hit a problem. However, most of the time sites blocked by OpenDNS (and, I have to still look at Google Public DNS more) are those which I would never want to go to.
Update based on your comments on YouTube in other answers.
If YouTube is really banned by your ISP (or higher authorities), changing to another DNS will usually not help (unless this 'ban' is very weakly implemented). You would need to investigate tunneling techniques to bypass such bans.