Mavericks Calendar sync with Google seems entirely broken?
Here's what worked for me:


Open Calendar.app
Open Preferences (⌘+,)
Click Accounts tab
Click plus button (+) to add an account
Select "Add CalDAV Account..."
Click Continue
Select "Account Type" Manual
Username is your full email address "yourname@gmail.com"
Password is your password (or application specific password if you use 2 factor auth)
Server Address is "https://www.google.com"


Notes:


Don't forget the "@gmail.com" on your gmail address! You can also use your own domain name if a Google Apps user
The "https://" on the Server Address field is critical. Without this you will get an error about not being able to establish a secure connection (https uses SSL where http doesn't).