diff --git a/geometry.py b/geometry.py
index d3219b1..b63cef3 100644
--- a/geometry.py
+++ b/geometry.py
@@ -2,6 +2,53 @@
 # -*- coding: utf-8 -*-
 
 
+class BaseGeometry(object):
+    """
+    Base geometry class sharing methods to child classes.
+    """
+
+    def __init__(self, coordinates: list):
+        self.coordinates = coordinates
+
+    @property
+    def coordinates(self) -> list:
+        """
+        Property getter for coordinates. Can be overwritten by child classes.
+        """
+        return self._coordinates if not None else list()
+
+    @coordinates.setter
+    def coordinates(self, coordinates: list):
+        """
+        Property setter for coordinates. Should be overwritten from child classes.
+        """
+        self._coordinates = coordinates
+
+    @coordinates.deleter
+    def coordinates(self):
+        self._coordinates = []
+
+    @property
+    def envelope(self) -> list:
+        """
+        Return the envelope or bounding box of the geometry.
+        """
+        min_x = float('inf')
+        min_y = float('inf')
+        max_x = float('-inf')
+        max_y = float('-inf')
+        for coordinate in self.coordinates:
+            if coordinate[0] < min_x:
+                min_x = coordinate[0]
+            if coordinate[1] < min_y:
+                min_y = coordinate[1]
+            if coordinate[0] > max_x:
+                max_x = coordinate[0]
+            if coordinate[1] > max_y:
+                max_y = coordinate[1]
+        return [min_x, max_x, min_y, max_y]
+
+
 class MyPolygon:
 
     def __init__(self, coordinates):
diff --git a/tests/test_geometry.py b/tests/test_geometry.py
index 8ff0df6..ffe9b2f 100644
--- a/tests/test_geometry.py
+++ b/tests/test_geometry.py
@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 
 
-from geometry import MyPolygon
+from geometry import MyPolygon, BaseGeometry
 
 
 def test_coordinates():
@@ -15,4 +15,17 @@ def test_coordinates():
 
 
 def test_envelope():
-    assert False
+    coordinates = [(1, 1), (1, 2), (2, 2), (2, 1), (1, 1)]
+    base_geometry: BaseGeometry = BaseGeometry(coordinates=coordinates)
+    assert [1, 2, 1, 2] == base_geometry.envelope
+
+
+def test_coordinates_setter_getter_deleter():
+    coordinates1 = [(1, 1), (1, 2), (2, 2), (2, 1), (1, 1)]
+    coordinates2 = [(1, 2), (1, 2), (2, 2), (2, 1), (1, 4)]
+    base_geometry: BaseGeometry = BaseGeometry(coordinates=coordinates1)
+    assert base_geometry.coordinates == coordinates1
+    base_geometry.coordinates = coordinates2
+    assert base_geometry.coordinates == coordinates2
+    del base_geometry.coordinates
+    assert base_geometry.coordinates == []