As a Filipino, I must say I'm proud to have the Mayon Volcano in my country. It's just the most perfectly cone-shaped mountain in the world, I believe. In a land filled to the brim with active volcanoes, this is the standout, just by the sheer beauty of it, not to mention it's one of the tallest (2400+ meters) stand-alone mountains in the archipelago. It has been quite active in the past few years, but when I visited back in 2012, the only things covering the perfect cone were the constant clouds.
The main viewpoints are from the Cagsawa Ruins and the Daraga Church, both of which are worth a visit for the sites themselves, by the way. Even in Cagsawa, the vast deposits of volcanic rock already tell the geological story of the volcano. However, as the listing follows the Natural Park itself, I claim a visit to the site through a visit to the Mayon Planetarium, 800 meters above sea level up the slopes of Mayon. I cannot however provide a picture of this, as it was stormy, and the peak was still surrounded by the clouds, so we did not take any pictures of the mountain itself. The planetarium visit personally didn't add much of relevance to the volcano, but on a clear day, would give an amazing view of the peak, which looks perfect from any direction and angle. If this alone doesn't justify inscription, surely its geological value as an important aspect of the Pacific Ring of Fire and biological impact to the adjacent environment's rich flora and fauna will do.
One day, I hope to climb or at least trek in the park to give a more comprehensive in-depth review of the site.