[jdsully]

The craziest part is these were built over very long periods of time spanning multiple generations. Inter-generational cooperation is just something I can't imagine happening today.

[robin_reala]

Köln cathederal was started in 1248 and finished in 1880 (albeit with a bit of a gap in the middle).

[twic]

The Sagrada Familia was started in 1882 and should be finished in 2026. That's a much shorter span, but it's entirely within the modern era.