There's a cathedral in a small university city outside Madrid that has already been a mosque once before. Now it's about to become one again  and the buyer is an Indonesian Islamic organization with 65 million members.

Muhammadiyah has purchased the Magisterial Cathedral of Saints Justo and Pastor in Alcalá de Henares, Spain, for approximately €3 million (around Rp45 billion). The deal, spearheaded by Muhammadiyah's East Java regional leadership and backed by the organization's central board, will convert the centuries-old building into a mosque and Islamic community center serving Alcalá de Henares' local Muslim population. The plan was first announced in November 2022 and has been unfolding in stages ever since.

At a glance:

• Price: ~€3 million (~Rp45 billion)
• Location: Alcalá de Henares, roughly 30 minutes from central Madrid
• First announced: November 2022, at Muhammadiyah's 48th Muktamar in Surakarta
• Architectural styles blended in the building: Romanesque, Gothic, Renaissance, Baroque, and Neoclassical

Where Exactly is this cathedral, and why does the location matter?

Alcalá de Henares isn't a random pick. It's a UNESCO World Heritage city, the birthplace of Miguel de Cervantes, and sits close enough to Madrid that a weekday commuter could make it in half an hour. The cathedral itself carries the rare title of "Magistral"  a designation reserved for churches whose clergy are required to hold a doctorate in theology. Only a handful of cathedrals in the world carry that status.

Walk past it today and you'd hear very little  the building has sat largely unused for years, its bell tower catching the late afternoon light over an otherwise quiet plaza. That silence is part of why it went up for sale in the first place.

Why is an Indonesian organization buying a cathedral in Spain?
This traces back to a specific meeting: the Sidang Pleno I of Muhammadiyah's 48th Muktamar, held in Surakarta in November 2022. There, Saad Ibrahim, chairman of Muhammadiyah's East Java regional leadership (PWM Jawa Timur), announced the organization's intent to establish a place of worship for Indonesian and local Muslims in Spain. The purchase is the execution of that pledge  part of a broader push to expand Muhammadiyah's dakwah (religious outreach) beyond Indonesia's borders.

There's also a layer of historical symbolism here that Muhammadiyah has leaned into. During the Umayyad era, when Muslim rule extended across Andalusia, the site is recorded as having functioned as a mosque before it was converted into a church following the Christian reconquest. Muhammadiyah's purchase effectively reverses that centuries-old shift.

"This commitment aims to restore Islamic civilization in Spain by providing better worship facilities for Muslims there," said Saad Ibrahim, chairman of PWM Jawa Timur, when the plan was first announced.

What happens to the building next?
Renovation and conversion plans are underway to transform the cathedral into a functioning mosque, alongside spaces for Islamic education, community coaching, and cultural activities aimed at both the local Indonesian diaspora and the wider Muslim community in the Alcalá de Henares area. Historically, the site has also hosted formal oath-takings and civic agreements  a detail that adds another layer to its long, layered past.

The surprising part most people miss: this isn't the first time this specific plot of land has switched religious functions. It has swung from mosque to church and, soon, back to mosque again  a rare architectural full circle.