I've seen a lot of interesting places on this trip, but Lalibela is simply extraordinary.
A thousand years ago the local king decided to build a church. There was no knowledge of brick buildings, so they carved the church out of the hillside. But, unlike Petra or Goreme, they dug down caving out whole structures - and then carved inside to create aisles and alters. It was, and remains an incredible and unique achievement.
The king wanted to create a pilgimage site for his people who could never hope to see Jerusalem. A thousand years later the people still have no hope of seeing Jerusalem, but will walk hundreds of miles to Lalibela. Especially for the time we were there, which was Ethiopian Orthodox Christmas (and the old king's saint's day).
This gives the place even more of a medieval feel, as pilgrims all wear the traditional white clothes to observe rituals that have never changed. Look out for one of my favourite pictures, 3036: every day over a thousand people would gather for an open air mass, just as they did a thousand years ago.