What is the smallest city in your country that everyone can still instantly recognise the name of? What is it famous for?
In the United States, I'd probably name Oregon City, the famous end of the Oregon Trail and the first city founded west of the Rocky Mountains during the pioneer era. Its population is only 37,000.
Schengen - the village in Luxembourg where the Schengen Agreement was signed. The population was 5196 in 2023 (appears to be the last census quoted on Wikipedia) and the "Schengen Area", covered by the agreement represents 450m people.
I thought so too before moving here, but there's two cities, and a lot of empty space (in the north in particular) with lots of towns and villages, it's not like Monaco or the Vatican City in that regard.
That being said, it's still all very close together, you can drive from the northern most point to the south in about 1.5-2 hours.
The funniest thing I've learned about the geography is that there is a North/South divide where people from either don't trust people from the other.