sudo mkdir /srv/www permission denied

I'm setting up a new webserver on Debian. As my previous install had everything located in /srv/www I want to use the same setup to avoid rewriting a bunch of config files. However executing mkdir /srv/www results in permission denied. Using both sudo as executing it as a su does not resolve the error. Permissions of /srv are set to drwxr-xr-x and I'm only using a single disk that's mounted on /. No nfs shares.