diff --git a/hub/exports/formats/geojson.py b/hub/exports/formats/geojson.py
index 429c6fc3..d9ef7dae 100644
--- a/hub/exports/formats/geojson.py
+++ b/hub/exports/formats/geojson.py
@@ -47,28 +47,66 @@ class Geojson:
 
   def _export(self):
     for building in self._city.buildings:
-      feature = self._feature_skeleton.copy()
+      if len(building.grounds) == 1:
+        ground = building.grounds[0]
+        feature = self._polygon(ground)
+      else:
+        feature = self._multipolygon(building.grounds)
       feature['id'] = building.name
-      feature['properties']['height'] = f'{building.max_height}'
+      feature['properties']['height'] = f'{building.max_height - building.lower_corner[2]}'
       feature['properties']['function'] = f'{building.function}'
       feature['properties']['year_of_construction'] = f'{building.year_of_construction}'
       feature['properties']['aliases'] = building.aliases
       feature['properties']['elevation'] = f'{building.lower_corner[2]}'
-      for ground in building.grounds:
-
-        ground_coordinates = []
-        for coordinate in ground.solid_polygon.coordinates:
-          gps_coordinate = self._to_gps.transform(coordinate[0], coordinate[1])
-          ground_coordinates.insert(0, [gps_coordinate[1], gps_coordinate[0]])
-
-        first_gps_coordinate = self._to_gps.transform(
-          ground.solid_polygon.coordinates[0][0],
-          ground.solid_polygon.coordinates[0][1]
-        )
-        ground_coordinates.insert(0, [first_gps_coordinate[1], first_gps_coordinate[0]])
-        feature['geometry']['coordinates'].append(ground_coordinates)
       self._geojson_skeleton['features'].append(feature)
     with open(self._file_path, 'w', encoding='utf-8') as f:
       json.dump(self._geojson_skeleton, f, indent=2)
 
+  def _polygon(self, ground):
+    feature = {
+      'type': 'Feature',
+      'geometry': {
+        'type': 'Polygon',
+        'coordinates': []
+      },
+      'properties': {}
+    }
+    ground_coordinates = []
+    for coordinate in ground.solid_polygon.coordinates:
+      gps_coordinate = self._to_gps.transform(coordinate[0], coordinate[1])
+      ground_coordinates.insert(0, [gps_coordinate[1], gps_coordinate[0]])
+
+    first_gps_coordinate = self._to_gps.transform(
+      ground.solid_polygon.coordinates[0][0],
+      ground.solid_polygon.coordinates[0][1]
+    )
+    ground_coordinates.insert(0, [first_gps_coordinate[1], first_gps_coordinate[0]])
+    feature['geometry']['coordinates'].append(ground_coordinates)
+    return feature
+
+  def _multipolygon(self, grounds):
+    feature = {
+      'type': 'Feature',
+      'geometry': {
+        'type': 'MultiPolygon',
+        'coordinates': []
+      },
+      'properties': {}
+    }
+    polygons = []
+    for ground in grounds:
+      ground_coordinates = []
+      for coordinate in ground.solid_polygon.coordinates:
+        gps_coordinate = self._to_gps.transform(coordinate[0], coordinate[1])
+        ground_coordinates.insert(0, [gps_coordinate[1], gps_coordinate[0]])
+
+      first_gps_coordinate = self._to_gps.transform(
+        ground.solid_polygon.coordinates[0][0],
+        ground.solid_polygon.coordinates[0][1]
+      )
+      ground_coordinates.insert(0, [first_gps_coordinate[1], first_gps_coordinate[0]])
+      polygons.append(ground_coordinates)
+    feature['geometry']['coordinates'].append(polygons)
+    return feature
+
 
diff --git a/hub/imports/geometry/citygml.py b/hub/imports/geometry/citygml.py
index ab36522f..9e5d5e8b 100644
--- a/hub/imports/geometry/citygml.py
+++ b/hub/imports/geometry/citygml.py
@@ -4,6 +4,7 @@ SPDX - License - Identifier: LGPL - 3.0 - or -later
 Copyright © 2022 Concordia CERC group
 Project Coder Guille Gutierrez guillermo.gutierrezmorote@concordia.ca
 """
+import logging
 
 import numpy as np
 import xmltodict
@@ -79,6 +80,7 @@ class CityGml:
             self._srs_name = envelope['@srsName']
           else:
             # If not coordinate system given assuming hub standard
+            logging.warning('gml file contains no coordinate system assuming EPSG:26911 (North america with 4m error)')
             self._srs_name = "EPSG:26911"
       else:
         # get the boundary from the city objects instead
diff --git a/tests/test_exports.py b/tests/test_exports.py
index c53a717c..61c69a93 100644
--- a/tests/test_exports.py
+++ b/tests/test_exports.py
@@ -100,7 +100,15 @@ class TestExports(TestCase):
 
   def test_geojson_export(self):
     self._export('geojson', False)
-    self.assertTrue(False, "False is not True")
+    geojson_file = Path(self._output_path / f'{self._city.name}.geojson')
+    self.assertTrue(geojson_file.exists(), f'{geojson_file} doesn\'t exists')
+    with open(geojson_file, 'r') as f:
+      geojson = json.load(f)
+    self.assertEqual(1, len(geojson['features']), 'Wrong number of buildings')
+    geometry = geojson['features'][0]['geometry']
+    self.assertEqual('Polygon', geometry['type'], 'Wrong geometry type')
+    self.assertEqual(1, len(geometry['coordinates']), 'Wrong polygon structure')
+    self.assertEqual(11, len(geometry['coordinates'][0]), 'Wrong number of vertices')
 
   def test_energy_ade_export(self):
     """