More than 140 years after the first stone was laid, Barcelona's Sagrada Família continues to rise.
Construction began in 1882, yet cranes still surround the basilica today as engineers work towards completing one of the most ambitious religious structures ever attempted.
Designed by Antoni Gaudí, the church is expected to become the world's tallest church upon completion, with the central Tower of Jesus Christ reaching 172.5 metres (566ft).
What makes the project remarkable is that many of its core engineering concepts were developed before modern computers, reinforced concrete skyscrapers, or digital modelling existed.
Gaudí relied on geometry, gravity, and observations from nature to solve structural problems that continue to fascinate architects and engineers.
