This book provides a visit to six cities in Golarion, the setting of the Pathfinder RPG. Before you invest in all the books, you can get this book and it provides a great "feel" for what Golarion is about.
The Six cities are;
Cassomir: The Port hub of the Taldor navy
Corentyn: The City of Nine Forts, a military town and know for its slave trade.
Ilizmagorti: The scum tide city, a city of pirates, scoundrels and assassins.
Nisroch: A city living in the shadow or a greater darkness.
Vigil: The city of music, joy and faith, the Last Wall defending freedom.
Whitethrone: A city in the frozen north, where monsters are more common than people