This is a guest post from a friend who is on the ground in Paris reporting what the situation is like.

The best way to begin might be to say that there are three distinct categories of Olympic games sites that the City of Paris wants to make ultra-safe for visitors and athletes, each with its own unique security challenges.

First, there are the many official, already-existing sporting venues (stadiums, arenas, tennis courts, aquatic centers, etc.) located throughout Paris and France. These require the least amount of novel security measures, whether in the form of protective perimeters or the (unusual) methods used to maintain them.

Included among these is the historic Grand Palais, an architectural jewel from 1900 located at the foot of the Champs-Elysées. A monumentally massive building with a marvelously versatile interior space, it regularly plays host to museum exhibitions of all types, in addition to galas, elaborate fashion shows, concerts, conventions, and even an ice-skating rink. Turning it into an Olympic sporting event site wouldn't have been very difficult.

Second, and complementing these dedicated sporting facilities, are several famous outdoor public monuments and historic landmarks that have been transformed into temporary games sites.

These comprise, most notably, the Trocadero and the area next to the Eiffel Tower, the Château de Versailles, the Place de la Concorde, the Alexandre III Bridge, and the expansive lawns in front of the Hôtel des Invalides.

Massive amounts of bleachers and facilities for ticketed spectators have been brought in and creatively set up to adapt to the often unusual contours and spatial constraints of these areas. Seeing the obelisk at la Place de la Concorde hidden behind a patchwork of crisscrossing bars and stands was strange indeed. From the outside, the expansive fenced-in area, with giant stands rising out from the emptied-out streets, looks like a curious sort of fairground.

Third, and arguably most importantly, there is the Seine River itself, which will be the location of the opening ceremony as well as several aquatic competitions.

From a security standpoint, the first category of venues is the most straightforward because entrances and exits are already part of the structures. All that is necessary to guarantee spectator and athlete safety is to set up slightly expanded perimeters around the buildings and flood the access points with staff and security guards so that no one – or anything – dangerous gets through.