Google may have had an ambiguous relationship with your data over the years, but with the expansion of privacy laws including GDPR and the huge rise of Cyber Security around the world has meant that data protection has been taken much more seriously by everyone,

I found this video today released by Google that defines the 6 layers of security they employ to maintain access control and oversight for the core place the hardware is kept,

Hope you enjoy the basics around physical security at a Google data centre, there is of course many more things you could add to tighten the controls and auditing more but they seem to have a pretty solid perimeter.