diff --git a/cartographer/mapping/3d/scan_matching/ceres_scan_matcher_3d.cc b/cartographer/mapping/3d/scan_matching/ceres_scan_matcher_3d.cc
index 16353e6..db71215 100644
--- a/cartographer/mapping/3d/scan_matching/ceres_scan_matcher_3d.cc
+++ b/cartographer/mapping/3d/scan_matching/ceres_scan_matcher_3d.cc
@@ -26,7 +26,7 @@
 #include "cartographer/mapping/3d/scan_matching/translation_delta_cost_functor_3d.h"
 #include "cartographer/mapping/internal/3d/rotation_parameterization.h"
 #include "cartographer/mapping/internal/3d/scan_matching/occupied_space_cost_function_3d.h"
-#include "cartographer/mapping/pose_graph/ceres_pose.h"
+#include "cartographer/mapping/internal/pose_graph/ceres_pose.h"
 #include "cartographer/transform/rigid_transform.h"
 #include "cartographer/transform/transform.h"
 #include "ceres/ceres.h"
diff --git a/cartographer/mapping/internal/2d/pose_graph/landmark_cost_function_2d.h b/cartographer/mapping/internal/2d/pose_graph/landmark_cost_function_2d.h
index 3b7eeda..997e4f2 100644
--- a/cartographer/mapping/internal/2d/pose_graph/landmark_cost_function_2d.h
+++ b/cartographer/mapping/internal/2d/pose_graph/landmark_cost_function_2d.h
@@ -20,7 +20,7 @@
 #include "Eigen/Core"
 #include "Eigen/Geometry"
 #include "cartographer/mapping/internal/2d/pose_graph/optimization_problem_2d.h"
-#include "cartographer/mapping/pose_graph/cost_helpers.h"
+#include "cartographer/mapping/internal/pose_graph/cost_helpers.h"
 #include "cartographer/mapping/pose_graph_interface.h"
 #include "cartographer/transform/rigid_transform.h"
 #include "cartographer/transform/transform.h"
diff --git a/cartographer/mapping/internal/2d/pose_graph/optimization_problem_2d.cc b/cartographer/mapping/internal/2d/pose_graph/optimization_problem_2d.cc
index 2c8d5a8..5e31729 100644
--- a/cartographer/mapping/internal/2d/pose_graph/optimization_problem_2d.cc
+++ b/cartographer/mapping/internal/2d/pose_graph/optimization_problem_2d.cc
@@ -29,7 +29,7 @@
 #include "cartographer/common/math.h"
 #include "cartographer/mapping/internal/2d/pose_graph/landmark_cost_function_2d.h"
 #include "cartographer/mapping/internal/2d/pose_graph/spa_cost_function_2d.h"
-#include "cartographer/mapping/pose_graph/ceres_pose.h"
+#include "cartographer/mapping/internal/pose_graph/ceres_pose.h"
 #include "cartographer/sensor/odometry_data.h"
 #include "cartographer/transform/transform.h"
 #include "ceres/ceres.h"
diff --git a/cartographer/mapping/internal/2d/pose_graph/spa_cost_function_2d.h b/cartographer/mapping/internal/2d/pose_graph/spa_cost_function_2d.h
index 75456a2..81d3bf8 100644
--- a/cartographer/mapping/internal/2d/pose_graph/spa_cost_function_2d.h
+++ b/cartographer/mapping/internal/2d/pose_graph/spa_cost_function_2d.h
@@ -22,8 +22,8 @@
 #include "Eigen/Core"
 #include "Eigen/Geometry"
 #include "cartographer/common/math.h"
+#include "cartographer/mapping/internal/pose_graph/cost_helpers.h"
 #include "cartographer/mapping/pose_graph.h"
-#include "cartographer/mapping/pose_graph/cost_helpers.h"
 #include "cartographer/transform/rigid_transform.h"
 #include "cartographer/transform/transform.h"
 #include "ceres/ceres.h"
diff --git a/cartographer/mapping/internal/3d/pose_graph/landmark_cost_function_3d.h b/cartographer/mapping/internal/3d/pose_graph/landmark_cost_function_3d.h
index 393be39..88fee28 100644
--- a/cartographer/mapping/internal/3d/pose_graph/landmark_cost_function_3d.h
+++ b/cartographer/mapping/internal/3d/pose_graph/landmark_cost_function_3d.h
@@ -20,7 +20,7 @@
 #include "Eigen/Core"
 #include "Eigen/Geometry"
 #include "cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d.h"
-#include "cartographer/mapping/pose_graph/cost_helpers.h"
+#include "cartographer/mapping/internal/pose_graph/cost_helpers.h"
 #include "cartographer/mapping/pose_graph_interface.h"
 #include "cartographer/transform/rigid_transform.h"
 #include "cartographer/transform/transform.h"
diff --git a/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d.cc b/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d.cc
index 8ba741b..198ce8a 100644
--- a/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d.cc
+++ b/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d.cc
@@ -36,7 +36,7 @@
 #include "cartographer/mapping/internal/3d/pose_graph/spa_cost_function_3d.h"
 #include "cartographer/mapping/internal/3d/rotation_cost_function_3d.h"
 #include "cartographer/mapping/internal/3d/rotation_parameterization.h"
-#include "cartographer/mapping/pose_graph/ceres_pose.h"
+#include "cartographer/mapping/internal/pose_graph/ceres_pose.h"
 #include "cartographer/transform/timestamped_transform.h"
 #include "cartographer/transform/transform.h"
 #include "ceres/ceres.h"
diff --git a/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d_test.cc b/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d_test.cc
index d561cb1..deeb9d1 100644
--- a/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d_test.cc
+++ b/cartographer/mapping/internal/3d/pose_graph/optimization_problem_3d_test.cc
@@ -21,7 +21,7 @@
 #include "Eigen/Core"
 #include "cartographer/common/lua_parameter_dictionary_test_helpers.h"
 #include "cartographer/common/time.h"
-#include "cartographer/mapping/pose_graph/optimization_problem_options.h"
+#include "cartographer/mapping/internal/pose_graph/optimization_problem_options.h"
 #include "cartographer/transform/transform.h"
 #include "glog/logging.h"
 #include "gmock/gmock.h"
diff --git a/cartographer/mapping/internal/3d/pose_graph/spa_cost_function_3d.h b/cartographer/mapping/internal/3d/pose_graph/spa_cost_function_3d.h
index 6654c13..98bacf8 100644
--- a/cartographer/mapping/internal/3d/pose_graph/spa_cost_function_3d.h
+++ b/cartographer/mapping/internal/3d/pose_graph/spa_cost_function_3d.h
@@ -22,8 +22,8 @@
 #include "Eigen/Core"
 #include "Eigen/Geometry"
 #include "cartographer/common/math.h"
+#include "cartographer/mapping/internal/pose_graph/cost_helpers.h"
 #include "cartographer/mapping/pose_graph.h"
-#include "cartographer/mapping/pose_graph/cost_helpers.h"
 #include "cartographer/transform/rigid_transform.h"
 #include "cartographer/transform/transform.h"
 #include "ceres/ceres.h"
diff --git a/cartographer/mapping/pose_graph/ceres_pose.cc b/cartographer/mapping/internal/pose_graph/ceres_pose.cc
similarity index 96%
rename from cartographer/mapping/pose_graph/ceres_pose.cc
rename to cartographer/mapping/internal/pose_graph/ceres_pose.cc
index 19a4788..fb993d6 100644
--- a/cartographer/mapping/pose_graph/ceres_pose.cc
+++ b/cartographer/mapping/internal/pose_graph/ceres_pose.cc
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "cartographer/mapping/pose_graph/ceres_pose.h"
+#include "cartographer/mapping/internal/pose_graph/ceres_pose.h"
 
 namespace cartographer {
 namespace mapping {
diff --git a/cartographer/mapping/pose_graph/ceres_pose.h b/cartographer/mapping/internal/pose_graph/ceres_pose.h
similarity index 88%
rename from cartographer/mapping/pose_graph/ceres_pose.h
rename to cartographer/mapping/internal/pose_graph/ceres_pose.h
index fc0de6a..31ed407 100644
--- a/cartographer/mapping/pose_graph/ceres_pose.h
+++ b/cartographer/mapping/internal/pose_graph/ceres_pose.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef CARTOGRAPHER_MAPPING_POSE_GRAPH_CERES_POSE_H_
-#define CARTOGRAPHER_MAPPING_POSE_GRAPH_CERES_POSE_H_
+#ifndef CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_CERES_POSE_H_
+#define CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_CERES_POSE_H_
 
 #include <array>
 #include <memory>
@@ -54,4 +54,4 @@ class CeresPose {
 }  // namespace mapping
 }  // namespace cartographer
 
-#endif  // CARTOGRAPHER_MAPPING_POSE_GRAPH_CERES_POSE_H_
+#endif  // CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_CERES_POSE_H_
diff --git a/cartographer/mapping/pose_graph/constraint_builder.cc b/cartographer/mapping/internal/pose_graph/constraint_builder.cc
similarity index 97%
rename from cartographer/mapping/pose_graph/constraint_builder.cc
rename to cartographer/mapping/internal/pose_graph/constraint_builder.cc
index fec217e..11cd89e 100644
--- a/cartographer/mapping/pose_graph/constraint_builder.cc
+++ b/cartographer/mapping/internal/pose_graph/constraint_builder.cc
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "cartographer/mapping/pose_graph/constraint_builder.h"
+#include "cartographer/mapping/internal/pose_graph/constraint_builder.h"
 
 #include "cartographer/mapping/2d/scan_matching/ceres_scan_matcher_2d.h"
 #include "cartographer/mapping/2d/scan_matching/fast_correlative_scan_matcher_2d.h"
diff --git a/cartographer/mapping/pose_graph/constraint_builder.h b/cartographer/mapping/internal/pose_graph/constraint_builder.h
similarity index 82%
rename from cartographer/mapping/pose_graph/constraint_builder.h
rename to cartographer/mapping/internal/pose_graph/constraint_builder.h
index 9463e26..2bc3125 100644
--- a/cartographer/mapping/pose_graph/constraint_builder.h
+++ b/cartographer/mapping/internal/pose_graph/constraint_builder.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef CARTOGRAPHER_MAPPING_POSE_GRAPH_CONSTRAINT_BUILDER_H_
-#define CARTOGRAPHER_MAPPING_POSE_GRAPH_CONSTRAINT_BUILDER_H_
+#ifndef CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_CONSTRAINT_BUILDER_H_
+#define CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_CONSTRAINT_BUILDER_H_
 
 #include "cartographer/common/lua_parameter_dictionary.h"
 #include "cartographer/mapping/pose_graph/proto/constraint_builder_options.pb.h"
@@ -31,4 +31,4 @@ proto::ConstraintBuilderOptions CreateConstraintBuilderOptions(
 }  // namespace mapping
 }  // namespace cartographer
 
-#endif  // CARTOGRAPHER_MAPPING_POSE_GRAPH_CONSTRAINT_BUILDER_H_
+#endif  // CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_CONSTRAINT_BUILDER_H_
diff --git a/cartographer/mapping/pose_graph/cost_helpers.h b/cartographer/mapping/internal/pose_graph/cost_helpers.h
similarity index 89%
rename from cartographer/mapping/pose_graph/cost_helpers.h
rename to cartographer/mapping/internal/pose_graph/cost_helpers.h
index 1c23e47..a9052a5 100644
--- a/cartographer/mapping/pose_graph/cost_helpers.h
+++ b/cartographer/mapping/internal/pose_graph/cost_helpers.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef CARTOGRAPHER_MAPPING_POSE_GRAPH_COST_HELPERS_H_
-#define CARTOGRAPHER_MAPPING_POSE_GRAPH_COST_HELPERS_H_
+#ifndef CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_COST_HELPERS_H_
+#define CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_COST_HELPERS_H_
 
 #include "Eigen/Core"
 #include "Eigen/Geometry"
@@ -63,6 +63,6 @@ std::array<T, 4> SlerpQuaternions(const T* const start, const T* const end,
 }  // namespace mapping
 }  // namespace cartographer
 
-#include "cartographer/mapping/pose_graph/cost_helpers_impl.h"
+#include "cartographer/mapping/internal/pose_graph/cost_helpers_impl.h"
 
-#endif  // CARTOGRAPHER_MAPPING_POSE_GRAPH_COST_HELPERS_H_
+#endif  // CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_COST_HELPERS_H_
diff --git a/cartographer/mapping/pose_graph/cost_helpers_impl.h b/cartographer/mapping/internal/pose_graph/cost_helpers_impl.h
similarity index 96%
rename from cartographer/mapping/pose_graph/cost_helpers_impl.h
rename to cartographer/mapping/internal/pose_graph/cost_helpers_impl.h
index 30b1c6f..bb0ab71 100644
--- a/cartographer/mapping/pose_graph/cost_helpers_impl.h
+++ b/cartographer/mapping/internal/pose_graph/cost_helpers_impl.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef CARTOGRAPHER_MAPPING_POSE_GRAPH_COST_HELPERS_IMPL_H_
-#define CARTOGRAPHER_MAPPING_POSE_GRAPH_COST_HELPERS_IMPL_H_
+#ifndef CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_COST_HELPERS_IMPL_H_
+#define CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_COST_HELPERS_IMPL_H_
 
 namespace cartographer {
 namespace mapping {
@@ -124,4 +124,4 @@ std::array<T, 4> SlerpQuaternions(const T* const start, const T* const end,
 }  // namespace mapping
 }  // namespace cartographer
 
-#endif  // CARTOGRAPHER_MAPPING_POSE_GRAPH_COST_HELPERS_IMPL_H_
+#endif  // CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_COST_HELPERS_IMPL_H_
diff --git a/cartographer/mapping/pose_graph/optimization_problem_options.cc b/cartographer/mapping/internal/pose_graph/optimization_problem_options.cc
similarity index 96%
rename from cartographer/mapping/pose_graph/optimization_problem_options.cc
rename to cartographer/mapping/internal/pose_graph/optimization_problem_options.cc
index 82d6f8e..0e57806 100644
--- a/cartographer/mapping/pose_graph/optimization_problem_options.cc
+++ b/cartographer/mapping/internal/pose_graph/optimization_problem_options.cc
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "cartographer/mapping/pose_graph/optimization_problem_options.h"
+#include "cartographer/mapping/internal/pose_graph/optimization_problem_options.h"
 
 #include "cartographer/common/ceres_solver_options.h"
 
diff --git a/cartographer/mapping/pose_graph/optimization_problem_options.h b/cartographer/mapping/internal/pose_graph/optimization_problem_options.h
similarity index 80%
rename from cartographer/mapping/pose_graph/optimization_problem_options.h
rename to cartographer/mapping/internal/pose_graph/optimization_problem_options.h
index 42fe5e5..d4b3a66 100644
--- a/cartographer/mapping/pose_graph/optimization_problem_options.h
+++ b/cartographer/mapping/internal/pose_graph/optimization_problem_options.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef CARTOGRAPHER_MAPPING_POSE_GRAPH_OPTIMIZATION_PROBLEM_OPTIONS_H_
-#define CARTOGRAPHER_MAPPING_POSE_GRAPH_OPTIMIZATION_PROBLEM_OPTIONS_H_
+#ifndef CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_OPTIMIZATION_PROBLEM_OPTIONS_H_
+#define CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_OPTIMIZATION_PROBLEM_OPTIONS_H_
 
 #include "cartographer/common/lua_parameter_dictionary.h"
 #include "cartographer/mapping/pose_graph/proto/optimization_problem_options.pb.h"
@@ -31,4 +31,4 @@ proto::OptimizationProblemOptions CreateOptimizationProblemOptions(
 }  // namespace mapping
 }  // namespace cartographer
 
-#endif  // CARTOGRAPHER_MAPPING_POSE_GRAPH_OPTIMIZATION_PROBLEM_OPTIONS_H_
+#endif  // CARTOGRAPHER_MAPPING_INTERNAL_POSE_GRAPH_OPTIMIZATION_PROBLEM_OPTIONS_H_
diff --git a/cartographer/mapping/pose_graph.cc b/cartographer/mapping/pose_graph.cc
index 65bda7f..7deb8fc 100644
--- a/cartographer/mapping/pose_graph.cc
+++ b/cartographer/mapping/pose_graph.cc
@@ -16,8 +16,8 @@
 
 #include "cartographer/mapping/pose_graph.h"
 
-#include "cartographer/mapping/pose_graph/constraint_builder.h"
-#include "cartographer/mapping/pose_graph/optimization_problem_options.h"
+#include "cartographer/mapping/internal/pose_graph/constraint_builder.h"
+#include "cartographer/mapping/internal/pose_graph/optimization_problem_options.h"
 #include "cartographer/transform/transform.h"
 #include "glog/logging.h"