Although it looks hundreds or even thousands of years old, this Coptic Christian church constructed out of Egypt's Mokattam Cliffs was only built in the 1970s. The Saint Simon Monastery serves a 30,000-person community called the Zabbaleen, who have traditionally scavenged items and collected garbage from the streets of Cairo. In 1969, the Zabbaleen were encouraged to leave the illegal makeshift settlements where they had been residing for this area. The first church built by the community burned down in a fire, so the decision was made to carve the next one, a massive monastery, directly into the cliffs via a pre-existing cave. The result is a marvel of rock-hewn construction, with seats for 20,000 worshippers around a central pulpit, and caves leading to separate churches in the complex. Indeed, the Saint Simon Monastery is now one of the largest churches in the Middle East.