Google has made it easier for you to export / archive your eMail or Calendars on your own hardware. The format of the data will be MBOX for eMail and iCal for calendar. To accomplish this, you will need to login to your Google account and follow this link: Download Google Data. You can archive everything or use the triangle on the left to reveal the option for selecting specific Folders or Calendars.
The archives will be processed and emailed to the account you are exporting the data from. Depending on how much data you have selected, will depend on how long it will take to archive. You can get addition information about this process from Google here.