diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 32797ee657..1a993a25cb 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -53,7 +53,6 @@ module Rails
     autoload :Bootstrap,      'rails/application/bootstrap'
     autoload :Configuration,  'rails/application/configuration'
     autoload :Finisher,       'rails/application/finisher'
-    autoload :Railties,       'rails/application/railties'
     autoload :RoutesReloader, 'rails/application/routes_reloader'
 
     class << self
@@ -83,27 +82,15 @@ module Rails
       @queue            = nil
     end
 
-    # This method is called just after an application inherits from Rails::Application,
-    # allowing the developer to load classes in lib and use them during application
-    # configuration.
-    #
-    #   class MyApplication < Rails::Application
-    #     require "my_backend" # in lib/my_backend
-    #     config.i18n.backend = MyBackend
-    #   end
-    #
-    # Notice this method takes into consideration the default root path. So if you
-    # are changing config.root inside your application definition or having a custom
-    # Rails application, you will need to add lib to $LOAD_PATH on your own in case
-    # you need to load files in lib/ during the application configuration as well.
-    def add_lib_to_load_path! #:nodoc:
-      path = File.join config.root, 'lib'
-      $LOAD_PATH.unshift(path) if File.exists?(path)
+    def initialized?
+      @initialized
     end
 
-    def require_environment! #:nodoc:
-      environment = paths["config/environment"].existent.first
-      require environment if environment
+    # Implements call according to the Rack API. It simples
+    # dispatch the request to the underlying middleware stack.
+    def call(env)
+      env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
+      super(env)
     end
 
     # Reload application routes regardless if they changed or not.
@@ -111,37 +98,6 @@ module Rails
       routes_reloader.reload!
     end
 
-    def routes_reloader #:nodoc:
-      @routes_reloader ||= RoutesReloader.new
-    end
-
-    # Returns an array of file paths appended with a hash of directories-extensions
-    # suitable for ActiveSupport::FileUpdateChecker API.
-    def watchable_args
-      files, dirs = config.watchable_files.dup, config.watchable_dirs.dup
-
-      ActiveSupport::Dependencies.autoload_paths.each do |path|
-        dirs[path.to_s] = [:rb]
-      end
-
-      [files, dirs]
-    end
-
-    # Initialize the application passing the given group. By default, the
-    # group is :default but sprockets precompilation passes group equals
-    # to assets if initialize_on_precompile is false to avoid booting the
-    # whole app.
-    def initialize!(group=:default) #:nodoc:
-      raise "Application has been already initialized." if @initialized
-      run_initializers(group, self)
-      @initialized = true
-      self
-    end
-
-    def initialized?
-      @initialized
-    end
-
     # Load the application and its railties tasks and invoke the registered hooks.
     # Check <tt>Rails::Railtie.rake_tasks</tt> for more info.
     def load_tasks(app=self)
@@ -179,6 +135,59 @@ module Rails
       })
     end
 
+    ## Rails internal API
+
+    # This method is called just after an application inherits from Rails::Application,
+    # allowing the developer to load classes in lib and use them during application
+    # configuration.
+    #
+    #   class MyApplication < Rails::Application
+    #     require "my_backend" # in lib/my_backend
+    #     config.i18n.backend = MyBackend
+    #   end
+    #
+    # Notice this method takes into consideration the default root path. So if you
+    # are changing config.root inside your application definition or having a custom
+    # Rails application, you will need to add lib to $LOAD_PATH on your own in case
+    # you need to load files in lib/ during the application configuration as well.
+    def add_lib_to_load_path! #:nodoc:
+      path = File.join config.root, 'lib'
+      $LOAD_PATH.unshift(path) if File.exists?(path)
+    end
+
+    def require_environment! #:nodoc:
+      environment = paths["config/environment"].existent.first
+      require environment if environment
+    end
+
+    def routes_reloader #:nodoc:
+      @routes_reloader ||= RoutesReloader.new
+    end
+
+    # Returns an array of file paths appended with a hash of
+    # directories-extensions suitable for ActiveSupport::FileUpdateChecker
+    # API.
+    def watchable_args #:nodoc:
+      files, dirs = config.watchable_files.dup, config.watchable_dirs.dup
+
+      ActiveSupport::Dependencies.autoload_paths.each do |path|
+        dirs[path.to_s] = [:rb]
+      end
+
+      [files, dirs]
+    end
+
+    # Initialize the application passing the given group. By default, the
+    # group is :default but sprockets precompilation passes group equals
+    # to assets if initialize_on_precompile is false to avoid booting the
+    # whole app.
+    def initialize!(group=:default) #:nodoc:
+      raise "Application has been already initialized." if @initialized
+      run_initializers(group, self)
+      @initialized = true
+      self
+    end
+
     # Returns the ordered railties for this application considering railties_order.
     def ordered_railties #:nodoc:
       @ordered_railties ||= begin
@@ -192,7 +201,7 @@ module Rails
           end
         end
 
-        all = (railties.all - order)
+        all = (railties - order)
         all.push(self)   unless (all + order).include?(self)
         order.push(:all) unless order.include?(:all)
 
@@ -216,11 +225,11 @@ module Rails
       @queue ||= build_queue
     end
 
-    def build_queue # :nodoc:
+    def build_queue #:nodoc:
       config.queue.new
     end
 
-    def to_app
+    def to_app #:nodoc:
       self
     end
 
@@ -228,20 +237,20 @@ module Rails
       config.helpers_paths
     end
 
-    def call(env)
-      env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
-      super(env)
+    def railties #:nodoc:
+      @railties ||= Rails::Railtie.subclasses.map(&:instance) +
+        Rails::Engine.subclasses.map(&:instance)
     end
 
   protected
 
     alias :build_middleware_stack :app
 
-    def reload_dependencies?
+    def reload_dependencies? #:nodoc:
       config.reload_classes_only_on_change != true || reloaders.map(&:updated?).any?
     end
 
-    def default_middleware_stack
+    def default_middleware_stack #:nodoc:
       ActionDispatch::MiddlewareStack.new.tap do |middleware|
         if rack_cache = config.action_controller.perform_caching && config.action_dispatch.rack_cache
           require "action_dispatch/http/rack_cache"
@@ -315,7 +324,7 @@ module Rails
     def initialize_runner #:nodoc:
     end
 
-    def build_original_fullpath(env)
+    def build_original_fullpath(env) #:nodoc:
       path_info    = env["PATH_INFO"]
       query_string = env["QUERY_STRING"]
       script_name  = env["SCRIPT_NAME"]
diff --git a/railties/lib/rails/application/railties.rb b/railties/lib/rails/application/railties.rb
deleted file mode 100644
index f20a9689de..0000000000
--- a/railties/lib/rails/application/railties.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require 'rails/engine/railties'
-
-module Rails
-  class Application < Engine
-    class Railties < Rails::Engine::Railties
-      def all(&block)
-        @all ||= railties + engines
-        @all.each(&block) if block
-        @all
-      end
-    end
-  end
-end
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 806b553b81..7db602279a 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -2,7 +2,6 @@ require 'rails/railtie'
 require 'active_support/core_ext/module/delegation'
 require 'pathname'
 require 'rbconfig'
-require 'rails/engine/railties'
 
 module Rails
   # <tt>Rails::Engine</tt> allows you to wrap a specific Rails application or subset of
@@ -338,7 +337,6 @@ module Rails
   #   config.railties_order = [Blog::Engine, :main_app, :all]
   class Engine < Railtie
     autoload :Configuration, "rails/engine/configuration"
-    autoload :Railties,      "rails/engine/railties"
 
     def initialize
       @_all_autoload_paths = nil
@@ -354,7 +352,7 @@ module Rails
 
     def load_generators(app=self)
       initialize_generators
-      railties.all { |r| r.load_generators(app) }
+      railties.each { |r| r.load_generators(app) }
       Rails::Generators.configure!(app.config.generators)
       super
       self
@@ -417,9 +415,11 @@ module Rails
       # Finds engine with given path
       def find(path)
         expanded_path = File.expand_path path
-        Rails::Engine::Railties.engines.find { |engine|
-          File.expand_path(engine.root) == expanded_path
-        }
+        Rails::Engine.subclasses.each do |klass|
+          engine = klass.instance
+          return engine if File.expand_path(engine.root) == expanded_path
+        end
+        nil
       end
     end
 
@@ -427,23 +427,23 @@ module Rails
     delegate :engine_name, :isolated?, :to => "self.class"
 
     def load_tasks(app=self)
-      railties.all { |r| r.load_tasks(app) }
+      railties.each { |r| r.load_tasks(app) }
       super
       paths["lib/tasks"].existent.sort.each { |ext| load(ext) }
     end
 
     def load_console(app=self)
-      railties.all { |r| r.load_console(app) }
+      railties.each { |r| r.load_console(app) }
       super
     end
 
     def load_runner(app=self)
-      railties.all { |r| r.load_runner(app) }
+      railties.each { |r| r.load_runner(app) }
       super
     end
 
     def eager_load!
-      railties.all(&:eager_load!)
+      railties.each(&:eager_load!)
 
       config.eager_load_paths.each do |load_path|
         matcher = /\A#{Regexp.escape(load_path)}\/(.*)\.rb\Z/
@@ -454,7 +454,7 @@ module Rails
     end
 
     def railties
-      @railties ||= self.class::Railties.new(config)
+      @railties ||= []
     end
 
     def helpers
@@ -507,7 +507,7 @@ module Rails
     end
 
     def ordered_railties
-      railties.all + [self]
+      railties + [self]
     end
 
     def initializers
diff --git a/railties/lib/rails/engine/railties.rb b/railties/lib/rails/engine/railties.rb
deleted file mode 100644
index 033d9c4180..0000000000
--- a/railties/lib/rails/engine/railties.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-module Rails
-  class Engine < Railtie
-    class Railties
-      # TODO Write tests for this behavior extracted from Application
-      def initialize(config)
-        @config = config
-      end
-
-      def all(&block)
-        @all ||= []
-        @all.each(&block) if block
-        @all
-      end
-
-      def self.railties
-        @railties ||= ::Rails::Railtie.subclasses.map(&:instance)
-      end
-
-      def self.engines
-        @engines ||= ::Rails::Engine.subclasses.map(&:instance)
-      end
-
-      delegate :railties, :engines, :to => "self.class"
-    end
-  end
-end
diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index 800b1c90f0..6071cd3f39 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -273,24 +273,18 @@ end
 # Create a scope and build a fixture rails app
 Module.new do
   extend TestHelpers::Paths
+
   # Build a rails app
-  if File.exist?(app_template_path)
-    FileUtils.rm_rf(app_template_path)
-  end
+  FileUtils.rm_rf(app_template_path)
   FileUtils.mkdir(app_template_path)
 
   environment = File.expand_path('../../../../load_paths', __FILE__)
-  if File.exist?("#{environment}.rb")
-    require_environment = "-r #{environment}"
-  end
+  require_environment = "-r #{environment}"
 
   `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/bin/rails new #{app_template_path}`
+
   File.open("#{app_template_path}/config/boot.rb", 'w') do |f|
-    if require_environment
-      f.puts "Dir.chdir('#{File.dirname(environment)}') do"
-      f.puts "  require '#{environment}'"
-      f.puts "end"
-    end
+    f.puts "require '#{environment}'"
     f.puts "require 'rails/all'"
   end
 end unless defined?(RAILS_ISOLATED_ENGINE)