In one of the holiest cities in Africa, rock-hewn churches have endured for centuries. But will they survive the modern age?

The city of Lalibela, high in the mountains of northern Ethiopia, has sat frozen in time for 800 years. Its 11 spectacular churches, carved out of the rocky ground—with the help of angels, according to legend—are still tended by white-robed priests who speak Geez, an ancient Semitic tongue. Hermits live in tiny caves in the churches' courtyard walls. And to millions of Ethiopian Coptic Christians, Lalibela remains the most sacred site in Africa.

But in the last four years, Lalibela has become the centerpiece of a government campaign to attract tourism to Ethiopia. Running water, electricity, and phone lines have been installed, an airport expanded, and plans announced to build a road to the capital, Addis Ababa. Many fear Lalibela isn't prepared to deal with the changes. The bishop, Abba Menbenu, worries about Western influences—satellite TV, tourists wearing Nikes—and their sway over young people, who no longer want to become priests.

But the modern world is also having positive effects. The European Union is helping to renovate five of the churches, which have been seriously eroded by years of wind and rain. Whether their congregations will persevere is another question.