Yeah, transport hubs especially airports but also some railway stations will often have conspicuously armed police patrolling. And high-profile government buildings. The UK gun of choice for this is the distinctive HK MP5 submachine gun.

Conversely if you want to see the use of the AR-15 in public artwork, you should go to Northern Ireland.

In Switzerland I once saw a conscript get on a train and put his rifle in the luggage rack exactly as if it were an umbrella. But Switzerland is different (guns are mandatory, ammunition heavily controlled, the people are the "militia" and support the government, and the whole country is a mountain fortress).

I've seen them walking around in train stations, airports, public squares and on the sidewalk. Remarkable from an American perspective.