  The circumference of a graph $G$ is the length of a longest cycle in $G$, or
$+\infty$ if $G$ has no cycle. Birmel\'e (2003) showed that the treewidth of a
graph $G$ is at most its circumference minus $1$. We strengthen this result for
$2$-connected graphs as follows: If $G$ is $2$-connected, then its treedepth is
at most its circumference. The bound is best possible and improves on an
earlier quadratic upper bound due to Marshall and Wood (2015).
