I've gotten a request for a castle cake similar to this one, but bigger, my question is, how do I go about covering this?  I thought about panels, but I'm worried about the 50 minute transport and having the panels fall off.  I usually use The Mat fondant system, but this needs to be embossed. Ideas anyone?  http://cakecentral.com/g/i/2128467/boys-castle-cake/u/744195/

AI would say you would cover it like any other cake. The pillars (cylinders) on the corners would be made separately, and attached after the cake is covered. Unless I'm not understanding your question.

I think you would be better off making panels for it, since it needs to be embossed with the stone pattern. I would make them some time ahead of having to attach them to the cake (like, a few days ahead). If you roll out, cut the panels, and then try to apply while fresh, you might have problems with it sagging due to the size of them. Good luck!

Most definitely panels which will also keep the embossing more crisp.

When I've done panels, I add some tylose/cmc/gum tex to my fondant and I allow them to set up for about 30 mins. before applying them to the cake.  I place the piece front side down on a clear flexible cutting mat so that I can line it up well with the cake.  I coat the back with some freshly melted chocolate and tip it up into place.

I agree with making panels.  What are you using under the fondant--buttercream or ganache?

This is how I covered a 10x10x10  "cardboard box" cake:  Roll out your fondant on wax, parchment, or freezer paper, emboss it, and cut out the panels to exactly the size you need for each side of the cake (leave a little room for the overlap so the panels join at the corners).  

When I made my cake, I skipped this next step because I didn't need to emboss my panels and you can skip it too and emboss later once the panel is on the cake...but I would recommend doing it this way instead   Use another sheet of wax, parchment or freezer paper and place that sheet on top of the embossed fondant.  At this point, your fondant should be sandwiched between two sheets of paper and you will sandwich it again between two cake boards that are large enough to support the entire panel.  Flip the whole thing over.  The embossed side should now be facing down.  Remove the top cake board and the top piece of paper and put the panel in the freezer for a few minutes.

Your fondant should be firm enough to pick up without stretching it out of shape.  Quickly apply the fondant panel to the side of the cake.  Line it up at the bottom and tip it up, and make sure all the edges line up.  Peel the bottom sheet off the fondant if it hasn't come off yet and smooth the fondant going up to move any air bubbles out the top. Work quickly because condensation will start to form--it's okay, just don't touch it again until the condensation has dried, otherwise you will have fingerprints.  This is why you need to work quickly to attach the fondant and make sure any air bubbles are smoothed out before the condensation starts.  If you decided to emboss after the panel is on the cake, you need to wait for the condensation to go away.  By this time, the fondant may be getting too dry to get a nice clean impression and why I recommend embossing it before you apply the panel to the cake.  

Don't try to do all the panels at once...only do one panel at a time and start with the top one, then the side panels.  Remember to add on a little extra height to the side panels to be even with the top panel.

If you use ganache under your fondant, when the cold fondant panel touches the chocolate, the chocolate will help set and hold the the fondant in place and you shouldn't have any issues with the panels coming off.  I don't use buttercream under fondant, so I don't know how the panels would hold up--sorry!

HTH!  Good luck!    

AWhen I do baby block cakes, cubes, I panel as well. And as suggested upthread, I add a bit of tylose to.the fondant to help it hold it's shape. I let it rest a bit before flipping it up into position, which I do with a cutting board, so I'm no tugging and stretching the panel out of shape. I use a razor blade to trim the edges off, once it's settled for a bit.

Thanks everyone for your advice, panels it is!  I'm feeling a lot more confident about this now.  I'll post pictures and let you know how it turned out with design, execution, and delivery.

I am going to give you a little bit different additional step. You make the panels by using stone impression mat and adding additional sections of "stones" by cutting portions out of impressed fondant. I have done this with great success in making stone floors so that you could not see the seam of where the panels joined. I just cut away the outside areas leaving a natural stone looking border and then cut out individual stones from a embossed panel in order to use to "seam" between panels. Hope this makes sense. If you look carefully at the picture you provided you can see the seam in the towers where her panel meets. My method eliminates this seam.