Martin Gabriel / Hiking trail along ancient aqueduct in Los Tilos National Park. World Biosphere Reserve, La Palma Island, Canary Islands, February.

Juan Manuel Borrero / Roman aqueduct, Tarragona, Catalonia, Spain. December 2003.

Juan Manuel Borrero / Carvao aqueduct with Chilean rhubarb (Gunnera tinctoria) at base. Devasa mountain range, Sao Miguel Island, Azores, Portugal. 2019.

Alan Williams / Pont-Cysyllte aqueduct over the River Dee, viewed from the east with the town of Trevor, in the background in the Vale of Llangollen North Wales, UK, September 2018.

Alan Williams / Pont-Cysyllte aqueduct over the River Dee viewed from the west side with a narrow boatcrossing in the Vale of Llangollen North Wales, UK, September.

Alan Williams / Pont-Cysyllte aqueduct over the River Dee viewed from the west side, Vale of Llangollen, North Wales, UK, September 2018.

Alan Williams / Pont Cysyllte Aqueduct, which takes the Llangollen canal across the River Dee, in autumn, Vale of Llangollen, near Trevor, North Wales, UK, October 2018.

Alan Williams / Pont-Cysyllte aqueduct over the River Dee viewed from the east with the town of Trevor in the background, Vale of Llangollen, North Wales, UK, September 2018.

Ashley Cooper / Pumping station sending water uphill over the mountains on the California aqueduct. This brings water from snowmelt in the Sierra Nevada mountains to farmland in the Central Valley. California, USA, S...

Ashley Cooper / Pumping station sending water uphill over the mountains on the California aqueduct. This brings water from snowmelt in the Sierra Nevada mountains to farmland in the Central Valley. California, USA, S...

Alan Williams / Canal barges crossing the Pont-Cysyllte aqueduct heading north over the River Dee near Trevor in the Vale of Llangollen North Wales UK September 2017

Alan Williams / Canal barges crossing the Pont-Cysyllte aqueduct, heading north over the River Dee, near Trevor in the Vale of Llangollen, North Wales, UK September 2017.

Alan Williams / Canal barges crossing the Pont-Cysyllte aqueduct, heading north over the River Dee, near Trevor in the Vale of Llangollen, North Wales, UK September 2017.

Alan Williams / Canal barges crossing the Pont-Cysyllte aqueduct, heading north over the River Dee, near Trevor in the Vale of Llangollen, North Wales, UK September 2017.

Alan Williams / Canal barges crossing the Pont-Cysyllte aqueduct, heading north over the River Dee, near Trevor in the Vale of Llangollen, North Wales, UK September 2017.

Alan Williams / Pont Cysyllte Aqueduct taking the Llangollen canal across the River Dee, Vale of Llangollen, near Trevor, North Wales, UK, September 2016.

Alan Williams / Barge crossing Pont Cysyllte Aqueduct, which takes the Llangollen canal, across the River Dee, Vale of Llangollen, near Trevor, North Wales, UK, September 2016.

Alan Williams / Pont Cysyllte Aqueduct taking the Llangollen canal across the River Dee, Vale of Llangollen, near Trevor, North Wales, UK, November 2016.

Alan Williams / Pont Cysyllte Aqueduct taking the Llangollen canal, across the River Dee, Vale of Llangollen, near Trevor, North Wales, UK, November 2016.

Alan Williams / Pont Cysyllte Aqueduct, taking the Llangollen canal, River Dee, Vale of Llangollen, near Trevor, North Wales, UK, November 2016.

Alan Williams / Pont Cysyllte Aqueduct taking the Llangollen canal across the River Dee in the Vale of Llangollen near Trevor North Wales UK November 54161

Alan Williams / Pont Cysyllte Aqueduct taking the Llangollen canal across the River Dee, Vale of Llangollen, near Trevor North, Wales, UK, September.

Alan Williams / Pont Cysyllte Aqueduct taking the Llangollen canal, across the River Dee, Vale of Llangollen, near Trevor, North Wales, UK, September 2016.

Graham Eaton / Pontcysyllte Aqueduct, built by Thomas Telford, carrying Llangollen Canal over River Dee, Wrexham, Denbighshire, Wales, UK, May, YEAR.

Graham Eaton / The Pontcysyllte Aqueduct carries the Llangollen Canal over the River Dee and its valley, near Wrexham, Wales, UK, a World heritage site.

Kerstin Hinze / Aerial view of crossing near Magdeburg of an artificial watercourse/ viaduct bridge crossing the Elbe River. Saxony-Anhalt, Germany, May 2012.

Rob Cousins / Boats moored in Brassknocker Basin near the junction with the Kennet and Avon Canal at Dundas Aqueduct, Wilshire, England

Rob Cousins / A modernised narrowboat moored in Brassknocker Basin near the junction with the Kennet and Avon Canal at Dundas Aqueduct, Wilshire, England

Rob Cousins / Boats moored in Brassknocker Basin near the junction with the Kennet and Avon Canal at Dundas Aqueduct, Wiltshire, England

Roland Seitre / Lesser kestrel (Falco naumanni) perched at entrance to nest hole in stone wall with insect prey in beak, M'Hamdia Aqueduct, Zaghouan, Tunisia.

Orsolya Haarberg / Levada, irrigation channel or aqueduct specific to Madeira, built to bring large amounts of water from the wetter west and northwest of the island to the drier southeast, which is more conducive to h...

Orsolya Haarberg / Levada, irrigation channel or aqueduct specific to Madeira, built to bring large amounts of water from the wetter west and northwest of the island to the drier southeast, which is more conducive to h...

Orsolya Haarberg / Levada, irrigation channel or aqueduct specific to Madeira, built to bring large amounts of water from the wetter west and northwest of the island to the drier southeast, which is more conducive to h...

Orsolya Haarberg / Levada in Folhadal. A levada is an irrigation channel or aqueduct specific to the Portuguese Atlantic region of Madeira. In Madeira, the levadas originated out of the necessity of bringing large amoun...

Nick Upton / Barge navigating the Dundas Aqueduct which carries the Kennet and Avon Canal over the River Avon, near Limpley Stoke, Wiltshire / Somerset border, UK, August.

Wayne Wu Ying / Wild Wonders of China / Photographers and local experts looking for amphibians and reptiles in aqueduct at night, Lantau Island, Hong Kong, China