It is perhaps the eighth wonder of our world that despite modern mapping and satellite photography our planet continues to surprise us. Hidden lairs beneath layers of rock, forgotten cities rising out of deserted lands and even mankind's own feats of engineering eccentricity lie in the most unusual of destinations. Travis Elborough goes in search of the obscure and bizarre, the beautiful and estranged. Taking in the defiant relics of ancient cities such as Ani, a once thriving metropolis lost to conquered lands, and the church tower of San Juan Parangaricuto, that miraculously stands as the sole survivor of a town sunk by lava.