One of the most amazing things I've ever seen was Spanish Catalan architect Antoni Gaudi's Sagrada Familia in Barcelona. The basilica looks like a giant drippy asymmetrical sandcastle. Gaudi started working on it in 1883. He was still working on it in 1926 when a tram ran over him and killed him. It was not complete when I visited it 20 years ago. This video shows what Sagrada Familia will look like when it is complete in 2026 (this is wishful thinking on their part). In a way, I hope they keep working on Sagrada Familia for as long as intelligent lifeforms exist on Earth - it's a worthy Long Now project.