One of the most famous architectural features of Prague in the Czech Republic is the 14th century Charles IV Bridge, which still maintains its medieval character.
The bridge replaced the earlier Judith's Bridge, which had been damaged by a flood in 1342 and had to be demolished. The new bridge was begun in 1357 with dimensions that were similar
to the one it was replacing: three meters wider and a few meters higher than the older one, but only fifteen pillars (as compared with twenty-one for the older bridge) and sixteen arches (compared to twenty-two).
The Old Town Bridge Tower is 30 meters tall, the Lesser Town Bridge Tower is 26 meters. Construction wasn't completed until the early fifteenth century; the famous sculptures on top of the
bridge were only completed in the 18th century. These depict the Crucifixion of Jesus, various saints, and other figures.
The first step in the construction was building a container around the future location of each pylon. Wooden walls were built into the riverbed, lined on the inside with aluminum,
then the water inside was pumped out with a large wheel containing buckets that lifted and dumped the water outside the enclosure to drain the entire interior down to the level of the riverbed.
Then a pylon was built inside each container, consisting of 5,000 tons of sandstone blocks held together with hydraulic lime mortar.
In between each pair of adjacent pylons, an arch was built using sandstone blocks on top of temporary wooden scaffolding, then the gaps between arches were filled in with stone blocks up to the level of the road.
The road on top of the bridge was then created with paving stones made of a hard rock such as diabase. Drainage was provided by holes leading to side gutters.
The animation below shows the steps in constructing the bridge, including the use of treadwheel-driven pile drivers, water pumps, and construction cranes: