Poland's second-largest city is also a major tourist destination. Krakow (seen here at night from the Krakus Mound) is suffering some of the worst air pollution in Europe. Arek Olek/Flickr hide caption

itoggle caption Arek Olek/Flickr

Berlin residents Mareike Geiling (left) and her boyfriend, Jonas Kakoschke, speak with their roommate, a Muslim refugee from Mali. Geiling and Kokoschke helped launch a website that matches Germans willing to share their homes with new arrivals. Soraya Sarhaddi Nelson/NPR hide caption

itoggle caption Soraya Sarhaddi Nelson/NPR

Earlier this month, Dr. Sadiqu al-Mousllie, accompanied by his family and a few members of their mosque, stood in downtown Braunschweig, Germany, and held up signs that read: "I am a Moslem. What would you like to know?" in an effort to promote dialogue between Muslims and non-Muslims. Courtesy of Sarah Mousllie hide caption

itoggle caption Courtesy of Sarah Mousllie

Jack Mandelbaum, a Holocaust survivor from the Polish city of Gdynia, poses in front of a photograph showing him as a youth. Tobias Schwarz/AFP/Getty Images hide caption

itoggle caption Tobias Schwarz/AFP/Getty Images