View list of all attachments on site

attachment.php file displays only one attachment (like single.php or page.php).

There is no way to list all attachments without coding. WordPress doesn’t have such list ready to use.

But it’s rather easy to do it by yourself.

Add your custom page template. Assign it to some page. And place something like this inside this template:

$args = array(
       'post_type'=>'attachment',  // you want to show attachments
       'posts_per_page'=>-1,  // all of them
// other params
);

$attachments = new WP_Query( $args );
while ( $attachments->have_posts() ): $attachments->the_post();
//display attachment - current attachment is placed in global variable $post 
// you can also use template tags
endwhile;