- Yokohama, Japan - since 1973
- Osaka, Japan - 1974
- Milan, Italy - 1979
- Rotterdam, the Netherlands - 1979
- San Francisco, United States - 1979
- Osaka Prefecture, Japan - 1980
- Zagreb, Croatia - 1980
- Hamhung, North Korea - 1982
- Manila, Philippines - 1983
- Antwerp, Belgium - 1984
- Karachi, Pakistan - 1984
- Chicago, United States - 1985
- Montreal, Canada - 1985
- Piraeus, Greece - 1985
- Gdańsk Voivodeship, Poland – 1985
- Nagasaki Prefecture, Japan - 1986
- Hamburg, Germany - 1986
- Casablanca, Morocco - 1986
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- Istanbul, Turkey - 1989
- Ho Chi Minh City, Vietnam - 1990
- Alexandria, Egypt - 1992
- Busan, South Korea - 1993
- Port Vila, Vanuatu - 1994
- Dunedin, New Zealand - 1994
- Haifa, Israel - 1994
- Tashkent, Uzbekistan - 1994
- Porto, Portugal - 1995
- Prague, Czech Republic[2]
- Aden, Yemen - 1995
- Windhoek, Namibia - 1995
- City of London, United Kingdom - 1996
- Santiago de Cuba, Cuba - 1996
- Rosario, Argentina - 1997
- Espoo, Finland - 1998
- Jalisco State, Mexico - 1998
- Liverpool, United Kingdom - 1999
- Maputo, Mozambique - 1999
- Dubai, United Arab Emirates - 2000
- Chiangmai, Thailand - 2000
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- KwaZulu Natal, South Africa - 2001
- Guayaquil, Ecuador - 2001
- Valparaíso, Chile - 2001
- Barcelona, Spain - 2001
- Oslo, Norway - 2001
- Constanţa, Romania - 2002
- Algiers, Algeria - 2003
- Colombo, Sri Lanka - 2003
- Aarhus County, Denmark - 2003
- Bratislava Region, Slovakia - 2003
- Hauraki District, New Zealand - 2003
- Salzburg, Austria - 2004
- Lefkosia, Cyprus - 2004
- Cork, Ireland - 2005
- Basel, Switzerland - 2007
- Borås, Sweden - 2007
- New York, United States - 2007
- Sarajevo, Bosnia and Herzegovina - 2008
- Manaus, Brazil - 2009
- Phnom Penh, Cambodia - 2009
- Greater London, United Kingdom - 2009
- Kuopio, Finland - 2012
- Seoul, South Korea - 2014
- Mumbai, India - 2014
- Bangkok, Thailand - 2014
- Houston, United States - 2014
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