Sagrada Família: Gaudí's Unfinished Masterpiece Nears Completion

143 Years Under Construction — and the Towers Are Finally Going Up

Ground was broken on the Sagrada Família on March 19, 1882 — the feast day of Saint Joseph. The first architect, Francisco de Paula del Villar, resigned within a year over a contractual dispute. Antoni Gaudí took over in 1883 at age 31, inherited a Neo-Gothic crypt already partially built, and spent the next 43 years reimagining the entire project into something the world had never seen. Gaudí died in 1926, struck by a tram in Barcelona, with roughly 25% of the church complete. Today, in 2026, the year the Foundation has targeted for structural completion of the central tower of Jesus Christ, the building finally approaches its intended silhouette — a skyline that Gaudí designed but never saw.

The Sagrada Família will have 18 towers when complete: 12 for the Apostles (already completed or nearly so), 4 for the Evangelists (three complete, one remaining), 1 for the Virgin Mary (completed in 2021 at 138 meters), and 1 central tower for Jesus Christ, designed to reach 172.5 meters — one meter shorter than Montjuïc hill, because Gaudí believed no human creation should surpass God's natural work. The 172.5-meter tower is being completed in 2026.

Gaudí's Structural Logic: Nature as Engineer

Gaudí rejected the Gothic flying buttress as a structural crutch — "crutches for weak structures," he called them. He sought structural forms that carried loads in pure compression, eliminating the tensile forces that masonry handles poorly. His solution came from nature and from mathematics: the catenary arch.

A catenary is the curve formed by a hanging chain or rope suspended from two endpoints under its own weight. Inverted, that curve becomes the ideal arch form for a structure under pure compression — no bending, no tension. To design the Sagrada Família's vaults and arches, Gaudí built large-scale hanging models using chains, string, and small bags of lead shot as weights. The resulting inverted catenary models, viewed upside-down in photographs, showed the exact structural form of the arches and vaults.

The Hanging Model: Design as Computation

Gaudí's workshop in Barcelona contained a large room dedicated to a single hanging model of the Sagrada Família's nave — approximately 4 meters in scale. Hundreds of strings hung from a framework corresponding to the building's plan, weighted with lead shot proportional to the structural loads at each point. Photographs of the inverted model were studied to verify structural form. If the strings (in compression when inverted) hung in catenary curves, the arches (those curves upright in stone) would stand in pure compression.

This is analog computation — a physical model performing calculations that Gaudí lacked the mathematics to perform analytically. The model was destroyed during the Spanish Civil War (1936), when anarchist forces torched Gaudí's workshop. Reconstruction was based on surviving photographs and fragments. The destruction of the models also destroyed much of Gaudí's design documentation, creating the interpretive challenge the Foundation has wrestled with ever since.

Parametric Design and Stone-Cutting Robots

After Gaudí's death, the project continued under successive architects who worked from partial drawings, models, and their interpretation of Gaudí's intent. The real transformation in construction pace came with digital tools. Beginning in the 1990s, the Foundation adopted CAD and later full parametric 3D modeling to reconstruct Gaudí's forms computationally — doing with software what Gaudí did with strings and lead shot.

• By the 2000s, all complex stone elements were being designed in 3D parametric models and cut by CNC (computer numerical control) stone-cutting robots to millimeter tolerances
• The hyperboloid surfaces and paraboloid geometries that define the Nativity facade and nave vaults are impossible to cut accurately by hand — CNC made them economically feasible
• Japanese computer scientist Hiroshi Toriumi contributed early computational analysis of Gaudí's forms in the 1980s–90s, helping the Foundation verify structural integrity
• The stone quarried for exterior cladding comes primarily from Montjuïc (now depleted for the Nativity facade), from Vilamacolum granite, and from Burgundy limestone for the interior

Construction Timeline and Financing

The Sagrada Família has been funded entirely by private donations and visitor entry fees since its inception — no government funding has ever been used for construction. Until the COVID-19 pandemic (which halted construction in 2020 and cost the Foundation an estimated €30 million in lost ticket revenue), approximately 4.5 million tourists per year visited, generating the construction budget. The Foundation resumed full construction pace by 2021.

The Unresolved Question of Authenticity

Critics — including some architects and Gaudí scholars — argue that the current Sagrada Família is not truly Gaudí's building but a reconstruction shaped by subsequent architects' interpretations, digital tools Gaudí never imagined, and aesthetic decisions that deviate from his documented intent. The Passion facade, designed by sculptor Josep Maria Subirachs (added 1987–2005), is angular and expressionistic in a way that directly contradicts Gaudí's preference for organic, nature-derived forms. Gaudí himself said he knew the church would take centuries and accepted that future architects would adapt his vision. Whether that ongoing adaptation preserves or transforms his work remains genuinely contested.