diff --git a/city_model_structure/city.py b/city_model_structure/city.py
index 3b4582df..40f80e98 100644
--- a/city_model_structure/city.py
+++ b/city_model_structure/city.py
@@ -1,11 +1,22 @@
-from city_model_structure.city_object import CityObject
+"""
+City module
+SPDX - License - Identifier: LGPL - 3.0 - or -later
+Copyright © 2020 Project Author Guille Gutierrez guillermo.gutierrezmorote@concordia.ca
+"""
+
+import sys
 from typing import List, Union
 import pyproj
 from pyproj import Transformer
 import reverse_geocoder as rg
+from city_model_structure.city_object import CityObject
 
 
 class City:
+  """
+  City class
+  """
+
   def __init__(self, lower_corner, upper_corner, srs_name, city_objects=None):
     self._city_objects = None
     self._name = None
@@ -16,16 +27,14 @@ class City:
     # todo: right now extracted at city level, in the future should be extracted also at building level if exist
     self._location = None
 
-  @property
-  def location(self):
+  def _get_location(self):
     if self._location is None:
       gps = pyproj.CRS('EPSG:4326')  # LatLon with WGS84 datum used by GPS units and Google Earth
-      input_reference = None
       try:
         input_reference = pyproj.CRS(self.srs_name)  # Projected coordinate system from input data
       except pyproj.exceptions.CRSError:
         print('Invalid projection reference system, please check the input data. (e.g. in CityGML files: srs_name)')
-        quit()
+        sys.exit()
       transformer = Transformer.from_crs(input_reference, gps)
       coordinates = transformer.transform(self.lower_corner[0], self.lower_corner[1])
       self._location = rg.search(coordinates)
@@ -33,33 +42,63 @@ class City:
 
   @property
   def country_code(self):
-    return self.location[0]['cc']
+    """
+    City country code
+    :return: str
+    """
+    return self._get_location()[0]['cc']
 
   @property
   def name(self):
+    """
+    City name
+    :return: str
+    """
     if self._name is None:
-      self._name = self.location[0]['name']
+      self._name = self._get_location()[0]['name']
     return self._name
 
   @property
   def city_objects(self) -> Union[List[CityObject], None]:
+    """
+    CityObjects belonging to the city
+    :return: None or a list of CityObjects
+    """
     return self._city_objects
 
   @property
   def lower_corner(self):
+    """
+    City lower corner
+    :return: [x,y,z]
+    """
     return self._lower_corner
 
   @property
   def upper_corner(self):
+    """
+    City upper corner
+    :return: [x,y,z]
+    """
     return self._upper_corner
 
   def city_object(self, name) -> Union[CityObject, None]:
-    for c in self.city_objects:
-      if c.name == name:
-        return c
+    """
+    Retrieve the city CityObject with the given name
+    :param name:str
+    :return: None or CityObject
+    """
+    for city_object in self.city_objects:
+      if city_object.name == name:
+        return city_object
     return None
 
   def add_city_object(self, new_city_object):
+    """
+    Add a CityObject to the city
+    :param new_city_object:CityObject
+    :return: None
+    """
     if self._city_objects is None:
       self._city_objects = []
     for city_object in self.city_objects:
@@ -70,8 +109,17 @@ class City:
 
   @property
   def srs_name(self):
+    """
+    srs name
+    :return: str
+    """
     return self._srs_name
 
   @name.setter
   def name(self, value):
+    """
+    Set the city name
+    :param value:
+    :return: None
+    """
     self._name = value
diff --git a/city_model_structure/thermal_boundary.py b/city_model_structure/thermal_boundary.py
index 552e664a..2b4c0eef 100644
--- a/city_model_structure/thermal_boundary.py
+++ b/city_model_structure/thermal_boundary.py
@@ -1,5 +1,5 @@
 from city_model_structure.thermal_opening import ThermalOpening
-from city_model_structure.surface import Surface
+from city_model_structure.thermal_zone import ThermalZone
 from city_model_structure.layer import Layer
 from helpers.configuration import Configuration
 from typing import List
@@ -21,7 +21,7 @@ class ThermalBoundary:
     self._shortwave_reflectance = None
 
   @property
-  def delimits(self) -> List[Surface]:
+  def delimits(self) -> List[ThermalZone]:
     return self._delimits
 
   @property
diff --git a/city_model_structure/thermal_opening.py b/city_model_structure/thermal_opening.py
index 159aee9d..9ad05494 100644
--- a/city_model_structure/thermal_opening.py
+++ b/city_model_structure/thermal_opening.py
@@ -3,7 +3,6 @@ from helpers.configuration import Configuration
 
 class ThermalOpening:
   def __init__(self):
-    self._area = None
     self._openable_ratio = None
     self._conductivity_w_mk = None
     self._frame_ratio = Configuration().frame_ratio
@@ -13,14 +12,6 @@ class ThermalOpening:
     self._outside_reflectance = None
     self._u_value = None
 
-  @property
-  def area(self):
-    return self._area
-
-  @area.setter
-  def area(self, value):
-    self._area = value
-
   @property
   def openable_ratio(self):
     raise Exception('Not implemented')
diff --git a/tests/test_geometry_factory.py b/tests/test_geometry_factory.py
index bbd36ac4..8b38d9a3 100644
--- a/tests/test_geometry_factory.py
+++ b/tests/test_geometry_factory.py
@@ -27,7 +27,6 @@ class TestGeometryFactory(TestCase):
     self.assertIsNotNone(city.upper_corner, 'upper_corner is none')
     self.assertIsNotNone(city.name, 'name is none')
     self.assertIsNotNone(city.country_code, 'country code is none')
-    self.assertIsNotNone(city.location, 'location is none')
 
   def test_citygml_city_objects(self):
     city = self.get_citygml()