Ubuntu Linux: where do the crontabs live?

I was doing a server migration on a server that runs a large number of cron jobs. I decided to pull the file over sftp so that I can easily copy the contents over to the new server. The only problem is I can never remember where the actual file resides. I seem to recall that spool was somewhere in the file path. I was betting on it not being very deep so I ran the following command.

find /*/spool

Which yielded the following results

/var/spool
/var/spool/cron
/var/spool/cron/atjobs
/var/spool/cron/atjobs/.SEQ
/var/spool/cron/atspool
/var/spool/cron/crontabs
/var/spool/cron/crontabs/root
/var/spool/rsyslog
/var/spool/mail

Which tells me the directory I am looking for is/var/spool/cron/crontabs and the full path is /var/spool/cron/crontabs/root as this crontab is ran by the root user.