Royal Icing recipe:
1 pound of confectionery sugar
1/4 teaspoon cream of tartar
3 egg whites
Beat slowly until stiff peaks form. Put icing in a pastry bag or a plastic bag with a hole cut in the bottom corner, which can serve as a pastry bag.
Use the icing to glue five graham crackers together (four walls and a roof), and allow to harden. Then use remaining icing to attach candy decorations.
Source: Historic Hotels of America press release. Historic Hotels of America is a program of the National Trust for Historic Preservation.
Need Gingerbread House inspiration? View these amazing photos of the winning creations at the 2008 Gingerbread House Competition in Boston.

