Authorities and businesses in Essen were preparing on Friday ahead of anticipated demonstrations against a weekend party congress of the far-right Alternative for Germany (AfD) being held in the western German city. Businesses around the congress venue in the Rüttenscheid area to the south of the city centre, boarded up their windows as a police helicopter circled overhead. Cars were being diverted away from the area, and the popular Grugapark with its open-air swimming pool was closed to visitors. Residents were asked to identify themselves before entering the area on foot only. Police are an…