Github: https://githubengineering.com/evolution-of-our-data-centers/
Backblaze: https://www.backblaze.com/blog/our-secret-data-center/
Twitter: https://blog.twitter.com/engineering/en_us/topics/infrastruc...
LinkedIn: http://www.datacenterdynamics.com/content-tracks/design-buil...
FastMail: https://www.fastmail.com/help/ourservice/security.html
Stack Overflow: http://highscalability.com/blog/2014/7/21/stackoverflow-upda...
Wikipedia: https://meta.wikimedia.org/wiki/Wikimedia_servers
OpenStreetMap: https://blog.openstreetmap.org/tag/infrastructure/
The Internet Archive: https://www.theregister.co.uk/2017/11/16/head_like_a_memory_...
Gitlab tried, but didn't have the necessary in-house experience before they made the attempt: https://about.gitlab.com/2017/03/02/why-we-are-not-leaving-t...
Instagram was migrated from AWS onto Facebook's infrastructure: https://www.wired.com/2014/06/facebook-instagram/
WhatsApp was migrated from IBM to Facebook infrastructure: https://www.cnbc.com/2017/06/07/facebook-planning-to-move-wh...
Hacker News and Pinboard (acq. Delicious) run on a single server.
It's not hard, but you do need to know what you're doing and have resources to do it (most orgs rent colo space in someone else's datacenter, they don't build their own). There's a reason AWS margins are so high (which leaves a lot of cost savings to be had when your workload isn't highly variable). Any questions, email is in my profile. I spent ~16 years building data centers, hosting environments, infrastructure, etc.