An estimated 5,500 people marched through Barcelona on Sunday to oppose the expansion of the city's airport, according to the City Police. The organizing platform, Zeroport, put the attendance at more than 30,000.

More than 250 organizations and collectives backed the demonstration, along with roughly 130 academics. The march set off at noon from Passeig de Gràcia under the slogan "No to the expansion, not now nor ever," and ended at Plaça de Sant Jaume, seat of the city government.

Around ten groups reached the starting point on foot, by bicycle, by metro and by train from locations across the Catalan capital and its metropolitan area. Participants described the atmosphere as festive, with speeches delivered at the closing rally.

The timing was deliberate. Spain's airport management authority approved its 2027–2031 investment plan this week, a package that includes funding to prepare for the Barcelona expansion. The plan allocates €17.6 billion across the Spanish airport network, and the Barcelona project is its single most contested component.

Zeroport said Sunday's turnout reflects the public's "outright opposition" to the expansion. Jaume Osete, the group's spokesperson, told demonstrators at the start of the march that the expansion would "exacerbate other societal problems."

The scale of opposition presents a political and operational constraint on a program designed to raise capacity at one of Europe's busiest airports. Local and regional resistance to airport growth has repeatedly delayed or reshaped expansion projects across the continent, and Barcelona's case now combines street-level protest, organized civil-society backing and academic support in a single coalition.

The gap between the police count and the organizers' figure — 5,500 versus more than 30,000 — is itself a measure of the contested political terrain. What is not contested is the investment plan's approval: funding for expansion preparation is now on the books for 2027 onward.

Whether that funding translates into construction on schedule will depend in part on how the Spanish government and the airport authority respond to opposition of this breadth. Zeroport has shown it can mobilize tens of thousands on short notice, and the demonstration's explicit slogan — opposition "not now nor ever" — leaves no room for negotiation over project design or timing.

The next indicators to watch are the formal steps within the investment plan's implementation: environmental review milestones, regional government positions, and any revision to the Barcelona allocation. Sunday's march suggests each of those steps will draw organized opposition.