For the first time ever, more people now live in cities than outside them. Veteran researcher and missiologist Patrick Johnstone explores the fastest growing cities and megacities, showing how Christian workers address people's spiritual, physical, and social needs. Cities offer both big headaches and vast opportunities, and agencies that once focused on rural work are increasingly turning their attention to urban centers. Patrick shares God's heart for the city and introduces pastors, missionaries, and community workers who are addressing urbanisation's key challenges.