(CNN) -- More than a million people took to the streets in Spain to rally for greater regional autonomy, police said.
The march in Barcelona on Saturday came after Spain's constitutional court ruled that the northeastern region of Catalonia could not refer to itself as a nation.
Protesters waved Catalonian flags and banners saying, "We are a nation. We decide." CNN sister network CNN+ showed images of regional leaders marching with a tennis-court sized flag.
Barcelona is the capital of Catalonia, one of 17 regions in Spain.
Conservatives have said Spain needs to be unified, a condition that fascist strongman Francisco Franco tried unsuccessfully to impose on the country from the end of the Spanish Civil War in 1939 until his death in 1975.