Months before September 11, 2001, many Greater New York churches were uniting together in one of the largest urban prayer movements in the world. So when disaster struck on that late summer Tuesday morning, the churches and people were already in place to comfort, heal and pray for miracles.Mac Pier and Katie Sweeting, coordinators for Concerts of Prayer Greater New York, write about their experiences in The Power of a City at Prayer. They explain how to build an urban prayer ministry, and they share powerful examples of how such prayer movements have dramatically influenced neighborhoods, communities and cities around the world--including New York City before and after September 11, 2001.