Germany's second largest city, Hamburg, hosted the G20 this week. With 6,000 delegates and 3,000 members of the global media flocking to the city, residents and the police braced themselves... and rightly so.
Adding to the problems created by the somewhat baffling choice of a city center location, Hamburg is home to a burgeoning left wing scene, far from shy to take to the streets.
Indeed, a number of protests took place, culiminating in Thursday's 'Welcome to Hell' march which ended in violent chaos, when around 8,000 leftwing radicals and anarchists descended on the location of the summit - the Congress Center - and fought with police.
Complicating the security operation further, the Congress Center is located on the edge of the 'Schanzenviertel', an area of the city much-loved and lived in by those involved with or sympathetic to left wing groups.
As Statista's Martin Armstrong details, according to the Hamburg police force, there are 1,090 known left wing extremists residing in the city, 620 of which are considered to be prone to violence. Looking to the whole of Germany, the figures grow to 26,700 and 7,700 respectively.
You will find more statistics at Statista
The resources required to police this huge group of people left less available for the ever-present threat of jihadist terrorism. In addition to the far-left and far-right, there are believed to be at least 640 Salafists living in Hamburg. 310 of these have been classified as jihadist.
In the worst case, this could have ended up leading to a perfect storm of chaos... so why did Merkel decide Hamburg city center was the right place to do this?
Judging by CNN's response to the riots - blaming Trump, and claiming that this has never happened before - the answer is simple politics.
Which of course is utter crap, as G-20 Summits have been crushed by protests and riots (not sure of the difference aside from level of violence) since at least as far back at Clinton in 1999...
In fact take your pick.
Obama in London in 2009...
Obama in Toronto in 2010...
To name just a few.