No one knows who placed the first of the hundreds of rusted anchors along the sand dunes of Praia do Barril Beach. But locals continued adding the gnarled weights to honor the small tuna fishing community that once flourished in the area.

The anchors were used to weigh down the nets for catching tuna. They’re lined up in rows and exist without any real pomp or officiality. Fishing in the area was a dangerous and difficult profession, but the unpredictable waters where the Atlantic meets the Mediterranean were bustling with bluefin tuna. The technique for catching them was unique to the area, and was probably invented by the ancient Romans who colonized the area.

Algarve thrived on tuna fishing for centuries, but local fisherman had to give up their occupation in the 1960s when the numbers of fish declined. Their anchors were just left on the beach to rust—until someone came up with the artistic idea.