Color murals by photographer Roland Halbe document the completed structures.

WSJ: Spain's Extraordinary Building Boom

The system, according to the researchers, makes spoofing the unique document fingerprints extremely difficult, if not impossible currently, because there is no way to replicate the surface structures artificially.

BBC: NEWS | Technology | Laser spots paper 'fingerprints'

This conference is another important step initiated by the International Centre on Qanats and Historic Hydraulic Structures (ICQHS) - a category 2 centre under the auspices of UNESCO - to collect and document traditional knowledge available on water resources management from around the globe while providing a forum for presenting new views on the topic.

UNESCO: Water Portal | Water Events Worldwide