Cover a piece of heavy cardboard with aluminum foil or freezer paper, dull-side up, to make a base for the gingerbread house.
Cut templates for the gingerbread house out of heavy cardboard or cardstock; label each piece.
Preheat oven to 350 degrees F (175 degrees C). Grease 3 rimless baking sheets (or the back of rimmed baking sheets).
Combine butter, brown sugar, molasses, and dark corn syrup in a large, heavy saucepan over medium heat; stir until melted, about 3 minutes. Stir in lemon zest, cinnamon, nutmeg, ginger, salt, and mace until blended, about 2 minutes. Remove from heat.
Sift flour into a large bowl. Stir into the butter mixture 2 cups at a time, mixing the last 2 cups by hand to create a warm, firm mass of dough. Place a large handful of dough on a greased baking sheet; roll out to 1/8-inch thickness. Keep remaining dough covered.
Dust cardboard templates lightly with flour and place on top of dough; cut around templates with a sharp knife. Cut out doors or windows as desired. Cut shutters, door knobs, or other features from the scraps. Return remaining scraps to the covered pan.
Bake in the preheated oven until firm and slightly browned at the edges, 5 to 7 minutes for small pieces and 12 to 15 minutes for large pieces. Remove from the oven and place templates over the baked pieces; trim excess with a sharp knife to produce clean edges.
Cool pieces on the baking sheet until firm, 5 to 10 minutes; transfer to a wire rack to cool completely, 15 to 30 minutes.
Combine confectioners' sugar, egg whites, cream of tartar, and white vinegar in the bowl of a stand mixer fitted with the paddle attachment; beat until icing is stiff and shiny, 7 to 10 minutes.
Stick candies and decorations over gingerbread pieces using royal icing. Let icing dry until hardened, about 5 minutes. Assemble gingerbread house pieces using icing. Let stand until icing is dry, about 5 minutes.