The Pantheon in Rome has stood for close to 1900 years. The rotunda is a coffered concrete dome with an opening revealing the sky. When it rains, it rains right into the building where the water flows to a drain. This is the world's largest unreinforced concrete dome to date. Michaelangelo declared when he saw the Pantheon that it was "angelic and not human design."
f/7, 1/200 sec, ISO 3200, 28-300 mm 3.5-5.6, Nikon D3S