Cities can play vital roles in international peace building when state-to-state relations are caught in stalemate. Cities can, for example, invite mayors and politicians of the other county and serve as an intermediary between their own state governments. Hosting dialogues, symposiums, workshops or cultural events is another way to facilitate mutual understanding and alleviate a sense of animosity among opinion leaders and general public. Cities can also take a lead in advancing collaboration for global common good (e.g. environmental protection) with foreign counterparts. Traditional practices such as "sister/twin cities" and "cultural capital" can be upgraded and invigorated for these purposes.