Slide toggle http://jsfiddle.net/nastysloper/v42EX/

index.html

<div id="tour">
  <h2>Paris, France Tour</h2>
  <p>$2,499 for 7 Nights</p>
  <button>See photos from our last tour</button>
  <ul class="photos">
    <li>
      <img src="/assets/photos/paris1.jpg">
      <span>Arc de Triomphe</span>
    </li>
    <li>
      <img src="/assets/photos/paris2.jpg">
      <span>The Eiffel Tower</span>
    </li>
    <li>
      <img src="/assets/photos/paris3.jpg">
      <span>Notre Dame de Paris</span>
    </li>
  </ul>
</div>

s.css

.photos {
    display: none;
}

slide.js

$(document).ready(function() { 
  $("#tour").on("click", "button", function() { 
    $(".photos").slideToggle();
  });
});