Castle: 1.Castle with 4 Towers and a Door

//------------------------------------------------
#declare Walltex = 
texture{pigment{color White}
        finish {ambient 0.15 diffuse 0.85 phong 1}}
#declare Rooftex =
texture{pigment{color rgb<0.4,0,0>}
        finish {ambient 0.15 diffuse 0.85 phong 1}}
#declare TR =  2.0;   //TowerRadius
#declare TH =  5.0;   //TowerHöhe
//--------------------  Tower  -------------------
#declare Tower= union{//defines object "Tower"
cylinder {<0,0,0>,<0,TH,0>,TR   texture{Walltex}}
cone{<0,0,0>,TR+0.5,<0,TR+0.5,0>,0
               translate<0,TH,0> texture{Rooftex}}
cone{<0,0,0>,TR -0.2,<0,2*TR+0.5,0>,0
               translate<0,TH,0> texture{Rooftex}}
}// ------------- end of the Tower-definition ----
// drawing "Tower" at the 4 angles:
object{ Tower translate<-6,0,-6>}
object{ Tower translate< 6,0,-6>}
object{ Tower translate< 6,0, 6>}
object{ Tower translate<-6,0, 6>}
//-----------------------------------------------
//------------------- Wall ----------------------
#declare Wall =
box {<-4,0,-0.3>,< 4,3.5,0.3>   texture{Walltex}}
// ------------- drawing 4 walls ----------------
difference{
 object{Wall} // Wall with holw for the door ---
 box{<-1,0,-0.4>,<1,2,0.4>       texture{Walltex}}
 cylinder{<0,2,-0.5>,<0,2,0.5>,1 texture{Walltex}}
                            translate< 0,0,-6>}
object{Wall rotate<0,  0,0> translate< 0,0, 6>}
object{Wall rotate<0, 90,0> translate<-6,0, 0>}
object{Wall rotate<0,-90,0> translate< 6,0, 0>}
// ---------------- Floor inside -----------------
box {<-6,-4,-6>,< 6,0.01,6>
     texture{pigment{color Gray90}
             finish {ambient 0.15 diffuse 0.85
                     phong 1}}}
//------------------------------------------end--