Where is El Capitan Calendar app data being stored on hard drive?

I'm running El Capitan, OS X 10.11.6. I'm trying to find where the Calendar app data is being stored on the hard drive. I "unhid" ~/Library/Calendars permanently via Terminal command (chflags nohidden ~/Library/) and can see my Microsoft Office 2011 for Mac calendar data in Finder, but not OS X Calendar app data. However, I can see the OS X Calendar data being backed up to iCloud, but I want to ensure that it's being backed up in my external drive via Time Machine. For example, what is the exact directory path where the files are stored (I don't see them in ~/Library/Calendars) and which file extensions should I be looking for? Thanks in advance.