Apache 2, Gentoo linux.
Sometimes Apache 2 may look for documents in /usr/htdocs, instead of in whatever directory you've specified in /etc/apache2/httpd.conf (with the DocumentRoot directive). This could be because you don't have a virtual host set up.
Apache should come with a default virtual host configuration in /etc/apache2/vhosts.d/00_default_vhost.conf. For a quick fix, enable the default virtual host by starting apache with the -D DEFAULT_VHOST option. Otherwise, create a new virtual host in /etc/apache2/vhosts.d/.