Tác giả: G. Richardson

It is now more than twenty years since a proposal was first mooted to hold an international tunnelling symposium in Britain. At the time of the first symposium, held in London in 1976, the Channel Tu …

Hidden by thick forest plants high in the Andes Mountains of South America, the Inca city of Machu Picchu lay abandoned for nearly 400 years. It was not until 1911 that it became active again. Find o …