Many New Zealanders will know Las Ramblas, one of the most pleasant streets in the world in one of the finest cities in the world, Barcelona. The Rambla, as English speaking tourists call it, is a tree-lined boulevard with fine buildings and alleys disappearing to its side, and a variety of street entertainment, different in every block.
It is always thronged with people.
It was a prime target for vehicle terrorism of the type seen in Nice last year, then Berlin, Westminster, London Bridge and now in Barcelona.
These are just of dozens of random acts of terrorism committed with a vehicle but each one causes a shudder at the ease with which it can be done. No explosives are required, no elaborate plans to plant a bomb, no suicide vests and volunteers for martyrdom. Just an ordinary van and a driver determined to run amok.
Cities are doing their best to guard against them. It is now common to see bollards strategically placed at the entrance to pedestrian precincts in central cities the world over. Many other barriers are disguised or designed so well they look like street furniture. But they will be solid enough to stop a motor vehicle.
But they will not deter the solitary psychotic, the so called "lone wolf", lacking access to more sophisticated weapons, using a vehicle to make a murderous mark on a society he hates. Lone wolves are always male, if females are involved in terrorism they are likely to have company, as in Germany's "red brigades" 50 years ago.
The van that ploughed into people in Barcelona on Thursday afternoon local time, killing 13 people, appears to have done the same thing as a few hours later, killing seven, in a town 100km away before Spanish police killed five of them in a shoot-out. So clearly it was not a lone wolf attack. The van had multiple occupants and they were wearing explosive belts, according to police.
The fading "Islamic State" was quick to claim its "soldiers" had carried out the attack in Barcelona but it is always an easy claim to make. Sadly, there seems to be no shortage of alienated young Middle Eastern migrants, or sons of migrants, in European cities who do not need a signal from Isis to strike at the West.
There is a limit to what bollards, counter-terrorism and shoot-outs can do to stop this scourge. It will end when migrant communities find their feet, which eventually, they do.