Almudena Cathedral
It was designed as long ago as 1879, but then the plans were changed to make it look like a 13th-century cathedral like the one in Rheims.  Building started in 1882, but during the Spanish Civil War no more work was done do it, and the building was not finished until the 1980s.  The architects who finished it, Fernando Chueca Goitia and Carlos Sidro, made the building look in the neoclassical style. It was consecrated in 1993 by Pope John Paul II.