PHP multiline string with PHP

I need to echo a lot of PHP and HTML.

I already tried the obvious, but it’s not working:

<?php echo '
<?php if ( has_post_thumbnail() ) {   ?>
      <div class="gridly-image"><a href="<?php the_permalink() ?>"><?php the_post_thumbnail('summary-image', array('class' => 'overlay', 'title'=> the_title('Read Article ',' now',false) ));?></a>
      </div>
      <?php }  ?>

      <div class="date">
      <span class="day">
        <?php the_time('d') ?></span>
      <div class="holder">
        <span class="month">
          <?php the_time('M') ?></span>
        <span class="year">
          <?php the_time('Y') ?></span>
      </div>
    </div>
    <?php }  ?>';
?>

How can I do it?

Answer

You don’t need to output php tags:

<?php 
    if ( has_post_thumbnail() ) 
    {
        echo '<div class="gridly-image"><a href="'. the_permalink() .'">'. the_post_thumbnail('summary-image', array('class' => 'overlay', 'title'=> the_title('Read Article ',' now',false) )) .'</a></div>';
    }

    echo '<div class="date">
              <span class="day">'. the_time('d') .'</span>
              <div class="holder">
                <span class="month">'. the_time('M') .'</span>
                <span class="year">'. the_time('Y') .'</span>
              </div>
          </div>';
?>