diff --git a/core/modules/block/block.admin.inc b/core/modules/block/block.admin.inc
index 7e6bcdb..b438c1f 100644
--- a/core/modules/block/block.admin.inc
+++ b/core/modules/block/block.admin.inc
@@ -153,8 +153,16 @@ function template_preprocess_block_admin_display_form(&$variables) {
     $block_listing[$region][$i]->row_class = !empty($block['#attributes']['class']) ? implode(' ', $block['#attributes']['class']) : '';
     $block_listing[$region][$i]->block_modified = !empty($block['#attributes']['class']) && in_array('block-modified', $block['#attributes']['class']);
     $block_listing[$region][$i]->block_title = $block['info'];
-    // @todo Remove these drupal_render() calls.
-    $block_listing[$region][$i]->region_select = drupal_render($block['region']) . drupal_render($block['theme']);
+    $block_listing[$region][$i]->region_select = array(
+      'region' => array(
+        'data' => $block['region'],
+        '#weight' => 1,
+      ),
+      'theme' => array(
+        'data' => $block['theme'],
+        '#weight' => 2,
+      ),
+    );
     $block_listing[$region][$i]->weight_select = $block['weight'];
     $block_listing[$region][$i]->operations = $block['operations'];
     $block_listing[$region][$i]->printed = FALSE;
diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index 72f8200..c0d8c9e 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -6,6 +6,7 @@
  */
 
 use Drupal\Component\Plugin\Exception\PluginException;
+use Drupal\Core\Template\Attribute;
 
 /**
  * Denotes that a block is not enabled in any region and should not be shown.
@@ -515,27 +516,29 @@ function block_rebuild() {
 }
 
 /**
- * Processes variables for block.tpl.php.
+ * Prepares variables for block templates.
+ *
+ * Default template: block.html.twig.
  *
  * Prepares the values passed to the theme_block function to be passed
  * into a pluggable template engine. Uses block properties to generate a
  * series of template file suggestions. If none are found, the default
- * block.tpl.php is used.
+ * block.html.twig is used.
  *
- * Most themes utilize their own copy of block.tpl.php. The default is located
- * inside "modules/block/block.tpl.php". Look in there for the full list of
+ * Most themes utilize their own copy of block.html.twig. The default is located
+ * inside "modules/block/block.html.twig". Look in there for the full list of
  * variables.
  *
- * The $variables array contains the following arguments:
- * - $block
- *
- * @see block.tpl.php
+ * @param array $variables
+ *   An associative array containing:
+ *   - elements: An associative array containing the properties of the element.
+ *     Properties used: #block, #block_config, #children.
  */
 function template_preprocess_block(&$variables) {
   $block_counter = &drupal_static(__FUNCTION__, array());
 
   $variables['block'] = (object) $variables['elements']['#block_config'];
-  $variables['subject'] = $variables['block']->subject;
+  $variables['label'] = check_plain($variables['elements']['#block']->label);
 
   // All blocks get an independent counter for each region.
   if (!isset($block_counter[$variables['block']->region])) {
@@ -548,6 +551,9 @@ function template_preprocess_block(&$variables) {
   // Create the $content variable that templates expect.
   $variables['content'] = $variables['elements']['#children'];
 
+  $variables['attributes'] = new Attribute;
+  $variables['attributes']['class'] = array();
+  $variables['attributes']['class'][] = 'block';
   $variables['attributes']['class'][] = drupal_html_class('block-' . $variables['block']->module);
 
   $variables['theme_hook_suggestions'][] = 'block__' . $variables['block']->region;
@@ -572,7 +578,7 @@ function template_preprocess_block(&$variables) {
   if ($id = $variables['elements']['#block']->id()) {
     $config_id = explode('.', $id);
     $machine_name = array_pop($config_id);
-    $variables['block_html_id'] = drupal_html_id('block-' . $machine_name);
+    $variables['attributes']['id'] = drupal_html_id('block-' . $machine_name);
     $variables['theme_hook_suggestions'][] = 'block__' . $machine_name;
   }
 }
diff --git a/core/modules/block/templates/block.html.twig b/core/modules/block/templates/block.html.twig
index 08eda19..01eb3c9 100644
--- a/core/modules/block/templates/block.html.twig
+++ b/core/modules/block/templates/block.html.twig
@@ -4,10 +4,10 @@
  * Default theme implementation to display a container.
  *
  * Available variables:
- * - subject: Block subject.
+ * - label: Block title.
  * - contents: The contents of this block.
- * - attributes: Remaining html attributes for the containing element.
- * - attributes.id: A valid html ID and guaranteed unique.
+ * - attributes: Remaining HTML attributes for the containing element.
+ * - attributes.id: A valid HTML ID and guaranteed unique.
  * - attributes.class: Classes that can be used to style contextually through
  *   CSS. These can be manipulated through from preprocess functions. The
  *   default values can be one or more of the following:
@@ -37,10 +37,10 @@
  @todo Remove the div around content - and make sure this doesn't break any
   CSS defined in modules.
 #}
-<div id="{{ block_html_id }}" class="{{ attributes.class }}"{{ attributes }}>
+<div id="{{ attributes.id }}" class="{{ attributes.class }}"{{ attributes }}>
   {{ title_prefix }}
-  {% if subject %}
-    <h2{{ title_attributes }}>{{ subject }}</h2>
+  {% if label %}
+    <h2{{ title_attributes }}>{{ label }}</h2>
   {% endif %}
   {{ title_suffix }}