The highest point in the City of Barcelona, Tibidabo, hosts both a church and an amusement park. They are found in remarkable proximity – close enough that a roller coaster passes the foundation of the church.
The most famous church in Barcelona is Gaudi’s masterpiece Sagrada Família. It’s a marvel of ambition, design, and the longest-running construction project in the city.

The second most famous is Sagrat Cor, situated at the top of Tibidabo, the highest point in the City of Barcelona. Not nearly as many tourists visit Sagrat Cor as Sagrada Familia, both because the interior is quite modest and it takes some effort to get there (it’s literally on top of the tallest hill in the city).

Sagrat Cor also seems like the greatest zoning failure of all time. That’s because an amusement park practically overlaps the church. Here’s a broader shot so that you can see what I mean:
There’s a roller coaster which runs along the base of the church, but remarkably, the roller coaster came first. The timeline is roughly:
1886-8: Hermitage built atop Tibidabo
1899: Amusement Park construction begins
1903-11: Crypt of Sagrat Cor built
1905: Tibidabo Amusement Park opens
1915-1951: Main Church of Sagrat Cor built
1952: Sagrat Cor consecrated
It seems that the church was willing to accept the proximity of the amusement park in exchange for building on the highest point in the city.
PS The word for “roller coaster” in Spanish is montaña rusa, which translates literally as “Russian mountain.” This is because our modern roller coasters originated as sleds on specially-constructed ice slides in St. Petersburg back in the 17th century.

