Use the find command.
If you didn't include your home directory, you could use locate as well, as in:
locate '/lib64/'
However it would show up for each subdirectory and file in '/lib64/', however you can filter that out:
locate '/lib64/' | sed 's#/lib64/.*$#/lib64#' | uniq
While this is more complicated, it is a lot quicker than running find. Especially since you are searching the entire filesystem. It would be better having some idea where things are, as in
find /tmp /home /var -type d -iname '*username*'
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