Add the tags to create an unordered list in an ordered list.

<html>
 <body>
  <ol>
   <li>Travel Destinations
    <ul>
     <li>Vienna</li> 
     <li>Bucharest</li>
     <li>Bratislava</li>
    </ul>
   </li>
  </ol>
 </body>
</html>
]]>

Add the <ol> tag and the <ul> tag. Then close the lists with </ul> and </ol>.