I'm a squarespace developer and clients came to me asking to create a site similar to Squarespace.com. I said that Squarespace.com is not done on Squarespace and to make squarespace site look like Squarespace.com requires a lot of custom code. But recently i've read this on squarespace help page: "For example, our own website is a Squarespace site, and it’s served from the same infrastructure we provide to our customers." Source.
Wow. Really a Squarespace site?