It's like Harry Potter before Harry Potter in Amsterdam city. We have 1/3th Basements and 1.3 street levels and every variation in between. It hardly ever is where you expect it. This town appears to be sunk. Factual the situation is the exact opposite. Amsterdam did not sink, it was build elevated. This makes sense considering the fact that the groundwater levels in Amsterdam are very high. The city was basically build in a swamp. Back in the day the options for watermanagement was unsubtile to say the least. In periods of heavy rains the basements would flood even though they where build above groundwater level.
In Amsterdam we have a very classy word for these basements. We call them "soutterains"the French word for basements. Don't be fooled by classy words. These spaces where used as kitchens and the cheapest housing for the poor. Rich people entered the houses by the staircases, well protected from the damp, fumes and floods. Water-management improved over the ages. Amsterdam does not flood anymore. Nowadays the 'soutterains" make great loft-appartements and they sell for prices comparable to apartments located in down-town London or New York.
Be warned! Especially when the sun has set you can make a nasty fall strolling alongside the canals of Amsterdam. I've seen the bottom of these staircases myself a couple of times. I'm clumsy when distracted...