People join hands to form a human chain linking the cities of San Sebastian, Vitoria and Bilbao, calling for a right to vote on Basque independence, in front of the Guggenheim Museum in Bilbao, Spain, June 10, 2018.
"The need to decide here in the Basque Country is what has brought together more than 175,000 people today".
The chain extended 201.9km from San Sebastian (also known as Donostia) to Victoria-Garteiz - the capital of the Basque autonomous community.
The Basque region, for instance, has more autonomy than any of Spain's other 16 regions, with its own police force, education system, language and a special financial relationship with Madrid.
The Spanish government, backed by the constitutional court, maintains that any ballot on regional independence is illegal.
The Spanish Constitution created in 1978 after the regime of dictator Francisco Franco, says that the country is indivisible, and the attempt of Catalonia to hold a referendum on separation in the past year were met with harsh prosecution.
Spain has refused to allow an official referendum on secession by the Catalonia region, whose leaders tried and failed to declare independence past year.
Calls for a vote on Basque nationality will provide a early test for Spain's new prime minister, Pedro Sanchez, who ousted his predecessor Mariano Rajoy in a vote of no confidence which he narrowly won thanks to support from Basque and Catalan nationalists.
Sanchez has called for renewed talks with the Catalan leadership since taking charge. However, he was stopped short of advocating for Catalonia or the Basque Country's right to full secession.