diff --git a/src/game/command.cr b/src/game/command.cr
index 06ba305..4a4b2f0 100644
--- a/src/game/command.cr
+++ b/src/game/command.cr
@@ -13,6 +13,7 @@ module Game
     end
 
     def start(world : World) : Int32
+      world.map.set(ConstructionSiteTile.new(@point))
       BUILD_TIME
     end
 
@@ -71,6 +72,7 @@ module Game
 
     def start(world : World) : Int32
       world.resources.dec(ResourceType::Crystal, CRYSTALS_COST)
+      world.map.set(ConstructionSiteTile.new(@point))
       BUILD_TIME
     end
 
@@ -122,6 +124,7 @@ module Game
     end
 
     def start(world : World) : Int32
+      world.map.set(ConstructionSiteTile.new(@point))
       world.resources.dec(ResourceType::Crystal, CRYSTALS_COST)
       BUILD_TIME
     end
diff --git a/src/game/map.cr b/src/game/map.cr
index cda262b..9dec3b2 100644
--- a/src/game/map.cr
+++ b/src/game/map.cr
@@ -39,7 +39,7 @@ module Game
     end
 
     def get(x : Int32, y : Int32) : Tile
-      @data[key(Point.new(x, y))]
+      get(Point.new(x, y))
     end
 
     def set(tile : Tile)
@@ -75,15 +75,6 @@ module Game
       seek_tile
     end
 
-    def print
-      (0...SIZE).each do |x|
-        (0...SIZE).each do |y|
-          printf "%c", @data[key(Point.new(x, y))].letter
-        end
-        printf "\n"
-      end
-    end
-
     private def key(p : Point) : String
       return sprintf "%d:%d", p.x, p.y
     end
diff --git a/src/game/tile.cr b/src/game/tile.cr
index 2120ac2..a343c37 100644
--- a/src/game/tile.cr
+++ b/src/game/tile.cr
@@ -1,5 +1,6 @@
 module Game
   enum TileRole
+    ConstructionSite
     CrystalDeposits
     CrystalHarvester
     CrystalRestorer
@@ -37,6 +38,10 @@ module Game
       charged = @cur + value
       @cur = charged <= @cap ? charged : @cap
     end
+
+    def can_build?
+      @role == TileRole::Plateau
+    end
   end
 
   class PlateauTile < Tile
@@ -49,6 +54,16 @@ module Game
     end
   end
 
+  class ConstructionSiteTile < Tile
+    def letter : Char
+      '_'
+    end
+
+    def has_role(role : TileRole) : Bool
+      role == TileRole::ConstructionSite
+    end
+  end
+
   class MainBaseTile < Tile
     def letter : Char
       'H'