diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index 3af30c8..0516510 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -355,7 +355,9 @@ function theme_admin_block_content($variables) {
 }
 
 /**
- * Returns HTML for an administrative page.
+ * Prepares variables for administrative index page templates.
+ *
+ * Default template: admin-page.html.twig.
  *
  * @param $variables
  *   An associative array containing:
@@ -366,40 +368,28 @@ function theme_admin_block_content($variables) {
  *
  * @ingroup themeable
  */
-function theme_admin_page($variables) {
-  $blocks = $variables['blocks'];
-
+function template_preprocess_admin_page(&$variables) {
+  $variables['system_compact_link'] = array(
+    '#theme' => 'system_compact_link',
+  );
+  $variables['containers'] = array();
   $stripe = 0;
-  $container = array();
-
-  foreach ($blocks as $block) {
-    $admin_block = array(
-      '#theme' => 'admin_block',
-      '#block' => $block,
-    );
-    if ($block_output = drupal_render($admin_block)) {
+  foreach ($variables['blocks'] as $block) {
+    $block = (array) $block;
+    if ($block['show'] = !empty($block['content'])) {
       if (empty($block['position'])) {
-        // perform automatic striping.
+        // Perform automatic striping.
         $block['position'] = ++$stripe % 2 ? 'left' : 'right';
       }
-      if (!isset($container[$block['position']])) {
-        $container[$block['position']] = '';
+      if (!isset($variables['containers'][$block['position']])) {
+        $variables['containers'][$block['position']] = array('blocks' => array());
       }
-      $container[$block['position']] .= $block_output;
+      $variables['containers'][$block['position']]['blocks'][] = array(
+        '#theme' => 'admin_block',
+        '#block' => $block,
+      );
     }
   }
-
-  $system_compact_link = array('#theme' => 'system_compact_link');
-  $output = '<div class="admin clearfix">';
-  $output .= drupal_render($system_compact_link);
-
-  foreach ($container as $id => $data) {
-    $output .= '<div class="' . $id . ' clearfix">';
-    $output .= $data;
-    $output .= '</div>';
-  }
-  $output .= '</div>';
-  return $output;
 }
 
 /**
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index ee3466d..eb75db6 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -170,6 +170,7 @@ function system_theme() {
     'admin_page' => array(
       'variables' => array('blocks' => NULL),
       'file' => 'system.admin.inc',
+      'template' => 'admin-page',
     ),
     'admin_block' => array(
       'variables' => array('block' => NULL),
diff --git a/core/modules/system/templates/admin-page.html.twig b/core/modules/system/templates/admin-page.html.twig
new file mode 100644
index 0000000..5a7d9b1
--- /dev/null
+++ b/core/modules/system/templates/admin-page.html.twig
@@ -0,0 +1,27 @@
+{#
+/**
+ * @file
+ * Default theme implementation for an administrative page.
+ *
+ * Available variables:
+ * - system_compact_link: Themed link to toggle compact view.
+ * - containers: An list of administrative blocks keyed by position: left or
+ *   right. Contains:
+ *   - blocks: A list of blocks within a container.
+ *
+ *
+ * @see template_preprocess_admin_page()
+ *
+ * @ingroup themeable
+ */
+#}
+<div class="admin clearfix">
+  {{ system_compact_link }}
+  {% for position, container in containers %}
+    <div class="{{ position }} clearfix">
+      {% for block in container.blocks %}
+        {{ block }}
+      {% endfor %}
+    </div>
+  {% endfor %}
+</div>