No, not like they did to Galveston Texas after the big hurricane. I’m thinking more along the lines of “Dang it, every time I try to dig a sewer trench I hit old stuff.”
One of the things that took a little getting used to in Europe was how cities climb over time. What had been ground level in the Roman or even pre-Roman eras may be twenty or more feet (six or more meters) under the street level today. Not by deliberate action, in most cases, but because that’s what cities do over time.
The cobblestones are the original street level. The gate is the modern street level. Krakow grew over time (since the early 1200s). How? Because people pulled down buildings, or dropped dirt, especially after the Mongol attacks and the great fire in the late 1200s, and built over the remains.
Cities increase in ground elevation over time, if given a long enough span of time. Now, this does not mean that all cities are higher than when founded. Houston, Venice, and others have sunk. Soil compression, when assisted by pumping the water out from under the cities, leads to settling and slumping. But most older cities in Europe are now higher than they were when founded, so what we see as cellars were the original ground floor, or even higher.
A few places, notably on the rivers leading to the North Sea and Baltic (the Hansa cities), were deliberately elevated after major floods. The ground floors became the cellars, or even secondary cellars, so that goods could be stored higher and out of danger of inundation. In some cases, excavators have found the old ground floor only by digging out a yard or so of dirt that centuries of flooding left behind. Streets also rose to match the house doors.
Vienna is another case where the city looks flatter than it really was, at least until you start poking around the really old part of the Altstadt.
Salzgasse, Judengasse, and the area “behind” them (toward St. Stephan’s Cathedral) seem to have at most a gentle slope, meaning the Danube Canal should be farther away unless there is a drop-off. Above you see the drop-off. You are not standing on a bluff. You are standing on the debris of ages. Roman ruins are under your feet, along with modern city stuff. And below the Roman? Even older, although there’s river sediment as well. And the Romans smoothed things over, literally, in order to have a nice, well-drained military settlement.
I fiddled with the exposure on the second photo to give a better contrast, but I took the pictures within seconds of each other. Again, you can see the old Roman road below. Far below. Very far below. Two blocks over is Salztorgasse, the northern end of the Roman settlement and where the salt gate was. The Danube Canal is one block to your right.
The church above, tucked in among modern stuff, was behind me in the two photos above. It is the oldest still standing and still used church in Vienna, and is a little unusual in that it is a night church, only open in the evenings and until midnight. St. Rupert is the patron saint of salt workers and salt traders, and the church is on Salzgasse, “Salt Alley.” ‘Salt Gate Street” is to your right, past Marcus Aurelius Street. The trees are growing on the bank of the Danube Canal. St. Rupert’s is about three meters – ten feet – above the FranzJosefKai, the pedestrian and traffic area between Vienna 1 and the canal. It is one of the oldest bits of rampart and wall still standing, and the oldest church still standing.
How old is the church? It was finished in AD 740 CE, but has been “updated” after fires and usage. There are arguments as to if it really is the oldest, but it is certainly the oldest currently in use with the original footprint. By tradition, it is the oldest. It probably incorporates the remains of a Roman shrine, but then what doesn’t in that part of the city? And you can see how high it sits compared to the old river edge.
There are other places where you can see how cities rise over time, but these are some of the clearest that I have good photos of.