Joomla layout override for menu item type = Category Blog. I'm using com_content as an event calendar showing the items grouped by month and by day. It's a copy from blog.php and on line 47 the override starts. A new array has been created to be able to group the items. (Thanks to @yireo for helping me with the creation of the new array) Using t…

agenda.php

<?php
/**
 * @package  	Joomla.Site
 * @subpackage	com_content
 * @copyright	Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
 * @license		GNU General Public License version 2 or later; see LICENSE.txt
 */

// no direct access
defined('_JEXEC') or die;

JHtml::addIncludePath(JPATH_COMPONENT.'/helpers');

?>
<div class="blog<?php echo $this->pageclass_sfx;?>">
<?php if ($this->params->get('show_page_heading')) : ?>
	<h1>
		<?php echo $this->escape($this->params->get('page_heading')); ?>
	</h1>
	<?php endif; ?>

	<?php if ($this->params->get('show_category_title', 1) or $this->params->get('page_subheading')) : ?>
	<h2>
		<?php echo $this->escape($this->params->get('page_subheading')); ?>
		<?php if ($this->params->get('show_category_title')) : ?>
			<span class="subheading-category"><?php echo $this->category->title;?></span>
		<?php endif; ?>
	</h2>
	<?php endif; ?>

	<?php if ($this->params->get('show_description', 1) || $this->params->def('show_description_image', 1)) : ?>
	<div class="category-desc">
	<?php if ($this->params->get('show_description_image') && $this->category->getParams()->get('image')) : ?>
		<img src="<?php echo $this->category->getParams()->get('image'); ?>"/>
	<?php endif; ?>
	<?php if ($this->params->get('show_description') && $this->category->description) : ?>
		<?php echo JHtml::_('content.prepare', $this->category->description, '', 'com_content.category'); ?>
	<?php endif; ?>
	<div class="clr"></div>
	</div>
	<?php endif; ?>

	<?php
	$introcount=(count($this->intro_items));
	$counter=0;
	
	$introItems = array();
	foreach($this->intro_items as $key => &$item) {
		$item_yearmonth = JHTML::_('date', $item->created, JText::_('F Y'));
		if(array_key_exists($item_yearmonth, $introItems) == false) {
			$introItems[$item_yearmonth] = array();
		}
		$item_date = $item->created;
		if(array_key_exists($item_date, $introItems[$item_yearmonth]) == false) {
			$introItems[$item_yearmonth][$item_date] = array();
		}
		$introItems[$item_yearmonth][$item_date][] = $item;
		
	}
	?>
<?php if (!empty($introItems)) : ?>
	<?php foreach ($introItems as $item_yearmonth_label => $item_days) : ?>
		<h2><?php echo $item_yearmonth_label; ?></h2>
		<?php foreach($item_days as $item_day_label => $item_day): ?>
			<dl class="dl-horizontal">
				<dt><?php echo JHTML::_('date', $item_day_label, JText::_('D d')); ?></dt>
				<dd><ul>
			<?php foreach($item_day as $item): ?>
				<li><p>
					<a href="<?php echo JRoute::_(ContentHelperRoute::getArticleRoute($item->slug, $item->catid)); ?>" title="<?php echo $this->escape($item->title); ?>"><?php echo $this->escape($item->title); ?></a> <span class="label"><?php echo $this->escape($item->category_title); ?></span><br/>
					<?php echo strip_tags($item->introtext); ?>
				</p></li>
			<?php endforeach; ?>
				</ul></dd>
		<?php endforeach; ?>
			</dl>
	<?php endforeach; ?>
<?php endif; ?>

	<?php if (($this->params->def('show_pagination', 1) == 1  || ($this->params->get('show_pagination') == 2)) && ($this->pagination->get('pages.total') > 1)) : ?>
	<div class="pagination">
		<?php  if ($this->params->def('show_pagination_results', 1)) : ?>
		<p class="counter">
			<?php echo $this->pagination->getPagesCounter(); ?>
		</p>
		<?php endif; ?>
		<?php echo $this->pagination->getPagesLinks(); ?>
	</div>
	<?php  endif; ?>
</div>