These days it is dominated by shops and throngs of people. But millions of years ago, Madrid’s Gran Via belonged to herds of 2-metre-long tortoises.

That’s the conclusion of a study published by Spanish and Greek researchers in the Zoological Journal of the Linnean Society. Wrapping up a 10-year study, researchers describe a genus of giant tortoises, previously unknown to science, that lived in Europe and western Asia between 20m and 2m years ago.

“We’re not just talking about any tortoise; this is the largest that lived in Europe, whose size likely exceeded that of the tortoises living today in the Galapagos Islands,” said researcher Adán Pérez-García, of Spain’s National University of Distance Education and the University of Lisbon.

The Titanochelon – a name inspired by their titanic size – was short, wide and strong, and its large shell was covered with ossified scales for protection, he said.

Researcher Adán Pérez-García with a fossilised Titanochelon in the Cerro de los Batallones (Hill of the Battalions) in Madrid. Photograph: Museo Nacional de Ciencias Naturales

Spanish palaeontologists hinted at the existence of the Titanochelon genus in the 1920s, but the civil war ended their research. Pérez-García and his team picked up where they left off, assuming that most of the material had disappeared.

But they found a wealth of fossils in Madrid’s National Museum of Natural Sciences, most of which had been untouched since the war. “The fossils were broken, samples were mixed up, it wasn’t clear where the material had come from,” he said. “But that’s what happens in a war. At least the material was there.”

The material turned out to be some of the best ever found of giant tortoises in Europe, said Pérez-García, citing the discovery of near-complete skeletons. “It allows us to imagine, with great precision, how millions of years ago, herds of giant tortoises wandered around what is now Gran Via.”