Gaudí wanted the basilica's interior to feel like a spiritual forest, using angled columns that distribute the heavy roof load more effectively than straight pillars.

Because the basilica is an expiatory church, construction relies entirely on alms and visitor ticket sales, explaining why the project has taken over a century.

The specific layout includes twelve towers for the apostles, four for the evangelists, one for the Virgin Mary, and the central, tallest spire for Jesus Christ.

Gaudí believed human creations should never exceed God's work, so he designed the central spire to be a few meters shorter than Barcelona's Montjuïc hill.