City life has come suddenly to modern Indonesia. Less than a century ago, only five percent of Indonesians lived in urban centres. Today, more than half of the population does. Indonesia's cities are places of growth, innovation, and inspiration. The country has embraced them, its successive governments making little attempt to control their explosive growth, and its citizens migrate to them more often because of the expanding urban opportunities rather than because of intensifying rural problems.
 
Yet now, as in the past, Indonesian cities are also arenas of confrontation and crisis. This is where cultures, classes, and faiths meet and sometimes clash, where disruptive as well as productive ideas are born; where an affluent creative class stands face to face with the poverty of the informal sector, and where commercial skyscrapers loom symbolically over past monuments of nation and faith.
 
Indonesian cities are also places where authorities and citizens wrestle with ecological and public health challenges of huge proportions. As river catchments are deforested and the sea level rises, disastrous flooding affects millions in densely populated coastal towns. There is also dangerous pollution of air and water from vehicles, industry, and domestic waste, and a wholesale transformation of the disease environment from one dominated by infection to one dominated by metabolic and cardiovascular problems, allergies, and asthma. Understanding the complex processes underlying the spread of such diseases in urban centres is crucial if we are to develop innovative responses to the global epidemic of non-communicable diseases.
 
Cities are where the future of Indonesia will be made and decided. Many of the challenges facing Indonesian cities echo similar challenges, past and present, in the Netherlands, long an urbanized country - albeit one without megacities - and one with a long history of urban planning, water management, and other interventions in relation to urban growth. The Urban Transitions programme is designed to focus and support international collaborative research between Indonesia and the Netherlands, and to promote sustainable inter- and multi-disciplinary approaches to old and new urban challenges, in both Indonesia and elsewhere.