well i can see the problem. is a standart type error.
if you look here you have a > in the first line, before </iframe> you have >. <iframe id="booking" runat="server" scrolling="no" frameborder="0" width="100%"> height="500" allowTransparency="true" src="
www.booking.com" ></iframe>
to make make it work the code work it should look like this <iframe id="booking" runat="server" scrolling="no" frameborder="0" width="100%" height="500" allowTransparency="true" src="
www.booking.com" ></iframe>
hope it will help.