If you cleared the room in the museum with his suit before you rescued Freeze then you have to return to the suit to move on.  If you rescued Freeze first then just go to the suit and you'll get it.  

Make sure you use your dive and pull up to gain some altitude.  Also, don't be afraid to use your grappling hook to get to the pillars if you are too low.  If you follow the trail left by Ra's then it is actually pretty easy.