Unfinished building is Antoni Gaudí's Sagrada Família in Barcelona, a church that has been under construction since 1882, and that is now expected to be complete in 2026. There are numerous unfinished buildings that remain partially constructed in countries around the world, some of which can be used in their incomplete state but with others remaining as a mere shell. Some projects are intentionally left with an unfinished appearance, particularly the follies of the late 16th to 18th century. Some buildings are in a cycle of near-perpetual construction, with work lasting for decades or even centuries. Antoni Gaudí's Sagrada Família in Barcelona,
Hyperboloid structure build the tower to 350m were not available. In July 1919, Lenin decreed that the tower should be built to a height of 150m, and the necessary steel was to be made available from the army's supplies. Construction of the smaller tower with six stacked hyperboloids began within a few months, and Shukhov Tower was completed by March 1922. Antoni Gaudi and Shukhov carried out experiments with hyperboloid structures practically simultaneously, but independently, in 1880–1895. Antoni Gaudi used structures in the form of hyperbolic paraboloid (hypar) and hyperboloid of revolution in the Sagrada Família in 1910. In the Sagrada Família,