diff --git a/README.md b/README.md
index 8096203..5df53a8 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ composer require mlocati/comuni-italiani
 
 This library provides the following Italian Administrative divisions:
 
-- **Geographical Subdivisions** (*ripartizioni geografiche*)  
+- **Geographical Subdivisions** (*ripartizioni geografiche*)
   For example "Nord-ovest", "Centro", "Sud"
 - **Regions** (*regioni*)
   For example "Piemonte", "Lazio", "Campania"
@@ -80,7 +80,7 @@ This library provides the following data:
   - the second level of the current Nomenclature of Territorial Units for Statistics (NUTS2) (example: `'ITC1'`)
   - the third level of the current Nomenclature of Territorial Units for Statistics (NUTS3) (example: `'ITC11'`)
 
-### Retrieving territories
+### Retrieving Territories
 
 You can have a list of all the Geographical Subdivisions, Regions, Provinces/UTS, and Municipalities using the `Factory` class.
 
@@ -110,7 +110,7 @@ $province = $finder->getProvinceByID('201');
 $municipality = $finder->getMunicipalityByID('001272');
 ```
 
-### Finding territories by name
+### Finding Territories by Name
 
 You can use the `Finder` class to find Geographical Subdivisions, Regions, Provinces/UTS, and Municipalities by name.
 
@@ -146,3 +146,26 @@ $regions = $finder->findRegionsByName('ampania', true);
 $provinces = $finder->findProvincesByName('ozen', true);
 $municipalities = $finder->findMunicipalitiesByName('oma ombard', true);
 ```
+
+### Testing Hierarchy
+
+Given two territories, you can check if they are the same by using the `isSame()` method:
+
+```php
+if ($territory1->isSame($territory2)) {
+    echo 'Same territory';
+}
+```
+
+For Geographical Subdivisions, Regions, and Provinces/UTS (which are containers of other territories) you can also use the `contains()` and `isSameOrContains()` methods.
+
+```php
+// $region is an instance of Region here
+if ($region->contains($territory)) {
+    echo "{$region} contains {$terrtory}";
+}
+
+if ($region->isSameOrContains($territory)) {
+    echo "{$region} is same (or contains) {$terrtory}";
+}
+```
diff --git a/src/GeographicalSubdivision.php b/src/GeographicalSubdivision.php
index a9f4a73..f93b784 100644
--- a/src/GeographicalSubdivision.php
+++ b/src/GeographicalSubdivision.php
@@ -9,6 +9,8 @@
  */
 final class GeographicalSubdivision implements TerritoryWithChildren
 {
+    use Service\TerritoryWithChildrenTrait;
+
     private array $data;
 
     private ?array $regions = null;
diff --git a/src/Municipality.php b/src/Municipality.php
index d141a0c..42d7785 100644
--- a/src/Municipality.php
+++ b/src/Municipality.php
@@ -9,6 +9,8 @@
  */
 final class Municipality implements Territory
 {
+    use Service\TerritoryTrait;
+
     private array $data;
 
     private Province $province;
diff --git a/src/Province.php b/src/Province.php
index 2c6c0b6..a72fa40 100644
--- a/src/Province.php
+++ b/src/Province.php
@@ -9,6 +9,8 @@
  */
 final class Province implements TerritoryWithChildren
 {
+    use Service\TerritoryWithChildrenTrait;
+
     private array $data;
 
     private Region $region;
diff --git a/src/Region.php b/src/Region.php
index b74950a..37e87c2 100644
--- a/src/Region.php
+++ b/src/Region.php
@@ -9,6 +9,8 @@
  */
 final class Region implements TerritoryWithChildren
 {
+    use Service\TerritoryWithChildrenTrait;
+
     private array $data;
 
     private GeographicalSubdivision $geographicalSubdivision;
diff --git a/src/Service/MultibyteTrait.php b/src/Service/MultibyteTrait.php
index 704575d..b7b20e4 100644
--- a/src/Service/MultibyteTrait.php
+++ b/src/Service/MultibyteTrait.php
@@ -4,6 +4,9 @@
 
 namespace MLocati\ComuniItaliani\Service;
 
+/**
+ * @internal
+ */
 trait MultibyteTrait
 {
     protected static function getMultibyteToAsciiMap(): array
diff --git a/src/Service/SorterTrait.php b/src/Service/SorterTrait.php
index a833cee..edeffaa 100644
--- a/src/Service/SorterTrait.php
+++ b/src/Service/SorterTrait.php
@@ -7,6 +7,9 @@
 use Collator;
 use MLocati\ComuniItaliani\Territory;
 
+/**
+ * @internal
+ */
 trait SorterTrait
 {
     use MultibyteTrait;
diff --git a/src/Service/TerritoryTrait.php b/src/Service/TerritoryTrait.php
new file mode 100644
index 0000000..35ad55a
--- /dev/null
+++ b/src/Service/TerritoryTrait.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MLocati\ComuniItaliani\Service;
+
+use MLocati\ComuniItaliani\Territory;
+
+/**
+ * @internal
+ */
+trait TerritoryTrait
+{
+    /**
+     * {@inheritdoc}
+     *
+     * @see \MLocati\ComuniItaliani\Territory::isSame()
+     */
+    public function isSame(Territory $territory): bool
+    {
+        return $this->getID() === $territory->getID();
+    }
+}
diff --git a/src/Service/TerritoryWithChildrenTrait.php b/src/Service/TerritoryWithChildrenTrait.php
new file mode 100644
index 0000000..66d2a9d
--- /dev/null
+++ b/src/Service/TerritoryWithChildrenTrait.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MLocati\ComuniItaliani\Service;
+
+use MLocati\ComuniItaliani\Territory;
+
+/**
+ * @internal
+ */
+trait TerritoryWithChildrenTrait
+{
+    use TerritoryTrait;
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see \MLocati\ComuniItaliani\TerritoryWithChildren::contains()
+     */
+    public function contains(Territory $territory): bool
+    {
+        foreach ($this->getChildren() as $child) {
+            if ($child instanceof TerritoryWithChildren) {
+                if ($child->isSameOrContains($territory)) {
+                    return true;
+                }
+            } elseif ($child->isSame($territory)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see \MLocati\ComuniItaliani\TerritoryWithChildren::isSameOrContains()
+     */
+    public function isSameOrContains(Territory $territory): bool
+    {
+        return $this->isSame($territory) || $this->contains($territory);
+    }
+}
diff --git a/src/Territory.php b/src/Territory.php
index de3ecd2..ab01de3 100644
--- a/src/Territory.php
+++ b/src/Territory.php
@@ -26,6 +26,11 @@ public function getParent(): ?TerritoryWithChildren;
      */
     public function getName(): string;
 
+    /**
+     * Check if a territory instance is the same as this.
+     */
+    public function isSame(Territory $territory): bool;
+
     /**
      * Get a string representation that uniquely represents the territory.
      */
diff --git a/src/TerritoryWithChildren.php b/src/TerritoryWithChildren.php
index f59774a..93ba9e8 100644
--- a/src/TerritoryWithChildren.php
+++ b/src/TerritoryWithChildren.php
@@ -15,4 +15,14 @@ interface TerritoryWithChildren extends Territory
      * @return \MLocati\ComuniItaliani\Territory[]
      */
     public function getChildren(): array;
+
+    /**
+     * Check if this territory contains another territory.
+     */
+    public function contains(Territory $territory): bool;
+
+    /**
+     * Check if this territory contains another territory, or if it's the same as this.
+     */
+    public function isSameOrContains(Territory $territory): bool;
 }
diff --git a/test/tests/HierarchyTest.php b/test/tests/HierarchyTest.php
new file mode 100644
index 0000000..5ceaca1
--- /dev/null
+++ b/test/tests/HierarchyTest.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MLocati\ComuniItaliani\Test;
+
+use PHPUnit\Framework\TestCase;
+use MLocati\ComuniItaliani\Factory;
+use MLocati\ComuniItaliani\Territory;
+use MLocati\ComuniItaliani\TerritoryWithChildren;
+
+class HierarchyTest extends TestCase
+{
+    public function testHierarchy(): void
+    {
+        $factory1 = new Factory();
+        $factory2 = new Factory();
+
+        $this->testHierarchyFor($factory1->getGeographicalSubdivisions()[0], $factory2->getGeographicalSubdivisions()[0]);
+    }
+
+    private function testHierarchyFor(Territory $territory, Territory $equalsNotSame): void
+    {
+        $this->assertNotSame($territory, $equalsNotSame);
+        $this->assertTrue($territory->isSame($territory));
+        $this->assertTrue($territory->isSame($equalsNotSame));
+        if ($territory instanceof TerritoryWithChildren) {
+            $this->assertFalse($territory->contains($territory));
+            $this->assertFalse($territory->contains($equalsNotSame));
+            $this->assertTrue($territory->isSameOrContains($territory));
+            $this->assertTrue($territory->isSameOrContains($equalsNotSame));
+            $child = $territory->getChildren()[0];
+            $this->assertFalse($child->isSame($territory));
+            $this->assertFalse($territory->isSame($child));
+            if ($child instanceof TerritoryWithChildren) {
+                $this->assertFalse($child->contains($territory));
+                $this->assertFalse($child->isSameOrContains($territory));
+                $this->testHierarchyFor($child, $equalsNotSame->getChildren()[0]);
+            }
+        }
+    }
+}