diff --git a/lib/entities/buildings/barracks.rb b/lib/entities/buildings/barracks.rb
index c36a94d..e29434f 100644
--- a/lib/entities/buildings/barracks.rb
+++ b/lib/entities/buildings/barracks.rb
@@ -1,4 +1,12 @@
-IMICRTS::Entity.define_entity(:barracks, :building, 400, "Builds and soldiers") do |entity|
+tiles = [
+  [false, false, false, false, false],
+  [false, true,  true,  true,  false],
+  [false, true,  true,  true,  false],
+  [false, true,  true,  true,  false],
+  [false, true,  true,  true,  false],
+]
+
+IMICRTS::Entity.define_entity(:barracks, :building, 400, "Builds and soldiers", tiles) do |entity|
   entity.has(:build_queue)
 
   entity.radius = 44
diff --git a/lib/entities/buildings/construction_yard.rb b/lib/entities/buildings/construction_yard.rb
index 67db116..d4756e7 100644
--- a/lib/entities/buildings/construction_yard.rb
+++ b/lib/entities/buildings/construction_yard.rb
@@ -1,4 +1,12 @@
-IMICRTS::Entity.define_entity(:construction_yard, :building, 2_000, "Provides radar and builds construction workers") do |entity|
+tiles = [
+  [false, false, false, false, false],
+  [false, true,  true,  true, false],
+  [false, true,  true,  true, false],
+  [false, true,  true,  true, false],
+  [false, true,  true,  true, false],
+]
+
+IMICRTS::Entity.define_entity(:construction_yard, :building, 2_000, "Provides radar and builds construction workers", tiles) do |entity|
   entity.has(:build_queue)
   entity.has(:sidebar_actions)
   entity.component(:sidebar_actions).add(:add_to_build_queue, {entity: :construction_worker})
diff --git a/lib/entities/buildings/helipad.rb b/lib/entities/buildings/helipad.rb
index ab1100a..a81ac49 100644
--- a/lib/entities/buildings/helipad.rb
+++ b/lib/entities/buildings/helipad.rb
@@ -1,4 +1,12 @@
-IMICRTS::Entity.define_entity(:helipad, :building, 1_000, "Builds and rearms helicopters") do |entity|
+tiles = [
+  [false, false, false, false, false],
+  [false, false, true,  false, false],
+  [false, true,  true,  true,  false],
+  [false, false, true,  false, false],
+  [false, false, false, false, false],
+]
+
+IMICRTS::Entity.define_entity(:helipad, :building, 1_000, "Builds and rearms helicopters", tiles) do |entity|
   entity.has(:build_queue)
   entity.has(:sidebar_actions)
   entity.component(:sidebar_actions).add(:add_to_build_queue, {entity: :helicopter})
diff --git a/lib/entities/buildings/power_plant.rb b/lib/entities/buildings/power_plant.rb
index aebcddc..bb0f30f 100644
--- a/lib/entities/buildings/power_plant.rb
+++ b/lib/entities/buildings/power_plant.rb
@@ -1,4 +1,12 @@
-IMICRTS::Entity.define_entity(:power_plant, :building, 800, "Generates power") do |entity|
+tiles = [
+  [false, false, false, false, false],
+  [false, false, false, false, false],
+  [false, false, true,  false, false],
+  [false, false, true,  false, false],
+  [false, false, true,  false, false],
+]
+
+IMICRTS::Entity.define_entity(:power_plant, :building, 800, "Generates power", tiles) do |entity|
   entity.radius = 24
   entity.max_health = 100.0
 
diff --git a/lib/entities/buildings/refinery.rb b/lib/entities/buildings/refinery.rb
index d95dc65..859ce2b 100644
--- a/lib/entities/buildings/refinery.rb
+++ b/lib/entities/buildings/refinery.rb
@@ -1,4 +1,12 @@
-IMICRTS::Entity.define_entity(:refinery, :building, 1_400, "Generates credits") do |entity|
+tiles = [
+  [false, false, false, false, false],
+  [false, true,  true,  true,  false],
+  [false, true,  true,  true,  false],
+  [false, true,  true,  true,  false],
+  [false, true,  true,  true,  false],
+]
+
+IMICRTS::Entity.define_entity(:refinery, :building, 1_400, "Generates credits", tiles) do |entity|
   entity.radius = 44
   entity.max_health = 100.0
 
diff --git a/lib/entities/buildings/war_factory.rb b/lib/entities/buildings/war_factory.rb
index 53fdb73..a2438ae 100644
--- a/lib/entities/buildings/war_factory.rb
+++ b/lib/entities/buildings/war_factory.rb
@@ -1,4 +1,12 @@
-IMICRTS::Entity.define_entity(:war_factory, :building, 2_000, "Builds units") do |entity|
+tiles = [
+  [false, false, false, false, false],
+  [false, true,  true,  true, false],
+  [false, true,  true,  true, false],
+  [false, true,  true,  true, false],
+  [false, true,  true,  true, false],
+]
+
+IMICRTS::Entity.define_entity(:war_factory, :building, 2_000, "Builds units", tiles) do |entity|
   entity.has(:build_queue)
   entity.has(:sidebar_actions)
   entity.component(:sidebar_actions).add(:add_to_build_queue, {entity: :jeep})
diff --git a/lib/entity.rb b/lib/entity.rb
index 6994b35..6ca604a 100644
--- a/lib/entity.rb
+++ b/lib/entity.rb
@@ -1,17 +1,17 @@
 class IMICRTS
   class Entity
-    Stub = Struct.new(:name, :type, :cost, :description, :setup)
+    Stub = Struct.new(:name, :type, :cost, :description, :tiles, :setup)
     @entities = {}
 
     def self.get(name)
       @entities.dig(name)
     end
 
-    def self.define_entity(name, type, cost, description, &block)
+    def self.define_entity(name, type, cost, description, tiles = [[]], &block)
       if entity = get(name)
         raise "#{name.inspect} is already defined!"
       else
-        @entities[name] = Stub.new(name, type, cost, description, block)
+        @entities[name] = Stub.new(name, type, cost, description, tiles, block)
       end
     end
 
diff --git a/lib/tool.rb b/lib/tool.rb
index 6d34857..c77b9db 100644
--- a/lib/tool.rb
+++ b/lib/tool.rb
@@ -41,6 +41,20 @@ class IMICRTS
     def cancel_tool
       @game.set_tool(nil)
     end
+
+    def use_tool(vector, options = {})
+    end
+
+    def can_use?(vector)
+    end
+
+    def vector_to_grid(vector)
+      temp = @player.camera.transform(vector)
+      temp.x = (temp.x / @director.map.tile_size).floor
+      temp.y = (temp.y / @director.map.tile_size).floor
+
+      return temp
+    end
   end
 end
 
diff --git a/lib/tools/place_entity.rb b/lib/tools/place_entity.rb
index 3f370cd..cefaf68 100644
--- a/lib/tools/place_entity.rb
+++ b/lib/tools/place_entity.rb
@@ -17,12 +17,33 @@ class IMICRTS
     def update
       # TODO: ensure that construction worker is alive
       cancel_tool if @construction_worker.die?
-      @preview.position = @player.camera.transform(@game.window.mouse)
-      @preview.position.z = ZOrder::OVERLAY
+      vector = vector_to_grid(@game.window.mouse)
+      if tile = @director.map.tile_at(vector.x, vector.y)
+        position = tile.position.clone
+        @preview.position = position
+        @preview.position.z = ZOrder::OVERLAY
+      else
+        @preview.position.z = -10
+      end
 
       @preview.color.alpha = 150
     end
 
+    def use_tool(vector)
+      return if @game.sidebar.hit?(@game.window.mouse_x, @game.window.mouse_y)
+
+      tile = @director.map.tile_at(vector.x, vector.y)
+      return unless tile
+      position = tile.position.clone
+
+      @director.spawn_entity(
+        player_id: @player.id, name: @entity,
+        position: CyberarmEngine::Vector.new(position.x, position.y, ZOrder::BUILDING)
+      )
+
+      cancel_tool
+    end
+
     def button_down(id)
       case id
       when Gosu::MsRight
@@ -33,16 +54,7 @@ class IMICRTS
     def button_up(id)
       case id
       when Gosu::MsLeft
-        return if @game.sidebar.hit?(@game.window.mouse_x, @game.window.mouse_y)
-
-        transform = @player.camera.transform(@game.window.mouse)
-
-        @director.spawn_entity(
-          player_id: @player.id, name: @entity,
-          position: CyberarmEngine::Vector.new(transform.x, transform.y, ZOrder::BUILDING)
-        )
-
-        cancel_tool
+        use_tool(vector_to_grid(@game.window.mouse))
       end
     end
   end