attachment.php

<?php
/**
 * The template for displaying all pages.
 *
 * This is the template that displays all pages by default.
 * Please note that this is the WordPress construct of pages
 * and that other 'pages' on your WordPress site may use a
 * different template.
 *
 * @link https://codex.wordpress.org/Template_Hierarchy
 *
 * @package underscore
 */

get_header(); ?>

	<div id="primary" class="content-area">
		<main id="main" class="site-main" role="main">

			<?php if(have_posts()) : while(have_posts()) : the_post(); ?>

<!-- Image title-->           

		<h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>

<!-- Full size image -->           
			
            <div class="entry-attachment">
<?php if ( wp_attachment_is_image( $post->id ) ) : $att_image = wp_get_attachment_image_src( $post->id, "full"); ?>
                        <p class="attachment"><a href="<?php echo wp_get_attachment_url($post->id); ?>" title="<?php the_title(); ?>" rel="attachment"><img src="<?php echo $att_image[0];?>" width="<?php echo $att_image[1];?>" height="<?php echo $att_image[2];?>"  class="attachment-medium" alt="<?php $post->post_excerpt; ?>" /></a>
                        </p>
<?php else : ?>
                        <a href="<?php echo wp_get_attachment_url($post->ID) ?>" title="<?php echo wp_specialchars( get_the_title($post->ID), 1 ) ?>" rel="attachment"><?php echo basename($post->guid) ?></a>
<?php endif; ?>
                        </div>
		</main><!-- #main -->
	</div><!-- #primary -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>