How do some of the most successful, leading cities in the world solve their problems? They steal the solutions — from other cities.

Before ramping up the number of bus lanes running through its high-rise canyons, Brazilian business hub Sao Paulo studied how such systems work in Paris, London, New York and Buenos Aires.

Feldman, a specialist on German foreign policy and international reconciliation, remarked that there are two kinds of public diplomacy. The first is carried out by the government and aims at improving the national image. The second concerns activities in which NGOs and other nongovernmental actors play the leading role. These activities might be described as “paradiplomacy,” or “transnationalism” in the case of projects that transcend national borders. She said that for public diplomacy to be successful, a partnership between government and non-government actors was essential.

What makes a city "cool"? If it means being loaded with atmosphere, charm, great food and nightlife, yet ignored by the bulk of travelers, then Lisbon deserves consideration as Europe's coolest capital. Here's why.

The southern French port city of Marseille has taken a bad rap for years. It’s known for thefts, violence and organized crime. But the city had a chance in 2013 to clean up its act, by being Europe’s rotating Capital of Culture for the year. The title means money from Europe to spiff up and boost local arts. Apparently it helped bring in more tourists. But the jury is out on whether Marseille is safer now, and whether local artists benefited from all the hoopla.

I first got a glimpse of Hawaiian public diplomacy a few years ago at the Taipei Flora Expo in 2011. Following a stint in Taiwan as a Visiting Fellow at a thinktank researching Taiwanese public diplomacy, I stopped in the Expo, which featured different countries exhibiting and showcasing their unique flora.

Last week, Rodrigo Tavares wrote in Foreign Affairs about Brazil’s recent involvement in paradiplomacy, or subnational foreign relations, by establishing formal bilateral relations between São Paulo and the UK. According to the article, the U.S. established a similar agreement with the world’s ninth largest city this past March - the first time that the State Department has forged direct relations with a subnational government in the southern hemisphere.