What's wrong with my code? Neighborhood Guides:Images 2


#1
<!DOCTYPE html>
<html>

  <head>
    <link href="http://s3.amazonaws.com/codecademy-content/courses/ltp/css/shift.css" rel="stylesheet">
    <link rel="stylesheet" href="http://s3.amazonaws.com/codecademy-content/courses/ltp/css/bootstrap.css">
    <link rel="stylesheet" href="main.css">
  </head>

  <body>

    <div class="nav">
      <div class="container">
        <ul class="pull-left">
          <li><a href="#">Name</a></li>
          <li><a href="#">Browse</a></li>
        </ul>
        <ul class="pull-right">
          <li><a href="#">Sign Up</a></li>
          <li><a href="#">Log In</a></li>
          <li><a href="#">Help</a></li>
        </ul>
      </div>
    </div>

    <div class="jumbotron">
      <div class="container">
        <h1>Find a place to stay.</h1>
        <p>Rent from people in over 34,000 cities and 192 countries.</p>
        <a href="#">Learn More</a>
      </div>
    </div>

    <div class="neighborhood-guides">
    <div class="container">
        <h2> Neighborhood Guides</h2>
        <p>Not sure where to stay? We've created neighborhood guides for cities all around the world.</p>

    <div class="row">
        <div class="col-md-4">
        <div class="thumbnail">
        <img src="http://goo.gl/0sX3jq">
        </div>
<div class="thumbnail">
<img src="http://goo.gl/an2HXY" >
    <div class="col-md-4">
    <div class="thumbnail">
    <img src="http://goo.gl/Av1pac">
    </div>
<div class="thumbnail">
<img src="http://goo.gl/vw43v1">
    <div class="col-md-4">
<div class="thumbnail">
<img src="http://goo.gl/0Kd7UO">
</div>
</div>
</div>
</div>

    <div class="learn-more">
      <div class="container">
        <div class="row">
          <div class="col-md-4">
            <h3>Travel</h3>
            <p>From apartments and rooms to treehouses and boats: stay in unique spaces in 192 countries.</p>
            <p><a href="#">See how to travel on Airbnb</a></p>
          </div>
          <div class="col-md-4">
            <h3>Host</h3>
            <p>Renting out your unused space could pay your bills or fund your next vacation.</p>
            <p><a href="#">Learn more about hosting</a></p>
          </div>
          <div class="col-md-4">
            <h3>Trust and Safety</h3>
            <p>From Verified ID to our worldwide customer support team, we've got your back.</p>
            <p><a href="#">Learn about trust at Airbnb</a></p>
          </div>
        </div>
      </div>
    </div>

  </body>
</html>

#2

That thumbnail is missing its closing tag, and so is the column that it is in.

The same goes for this one.