World wide, we see developing nations building new infrastructure as well as developed cities rehabilitating and expanding their infrastructure to meet the demands of increased population, energy efficiency, and environmental awareness of the public. Ten years ago ITA issued its special edition of the Tribune entitled “Why Go Underground, Contribution of the use of Underground space to Sustainable Development.” Working Group N° 20 of the ITA, focused on Urban Problems and Underground Solutions, has continued examining the use of underground space in the urban environment as it evolves with expanding cities and urban densification. This report present examples of the uses of underground space in cities, trends in Metro and roadway planning, and gives an overview of aspects to be considered during the decision making process, in order to optimally include underground solutions.