This animation shows how the 14th-century Charles Bridge was built in Prague.Here's the video description, machine-translated:
The digital model "Charles Bridge – construction of a pillar and vaulted field in the 14th century" was created for the project of the virtual exhibition Prague of the time of Charles IV. The project is supported by the Ministry of Culture of the Czech Republic as part of the National Celebrations of the 700th Anniversary of the Birth of Emperor Charles IV. and is included in the AV21 Strategy program.
I watched this thinking "wow, that's a lot more complicated and elaborate than I thought it would be." It took them 45 years. Forthcoming repairs will take another 20.