Petra was carved out of red sandstone in the 3rd century BC by the Nabateans. The only entrance to the city is through a long, narrow gorge, known as the 'siq' which stretches for about 2km and sometimes no wider than a couple of metres.
Seeing a volcano erupt is a once-in-a-lifetime experience and in Guatemala, you can actually climb one and feel the heat of it as it erupts. No, I'm not crazy!