For 2018 Valletta shares the honour with Leeuwarden in The Netherlands.
Months of political turmoil have ended in Kenya with the swearing in of President Uhuru Kenyatta for a second, five-year term.
French president Emmanuel Macron and his wife Brigitte joined Abu Dhabi's Crown Prince and Dubai's ruler at the official opening of the Louvre Abu Dhabi.
Paul Kagame has been sworn in for another sucessive term as President of Rwanda, a job he has held since 2000.
Venezuela's controversial new constituent assembly has been sworn in despite worldwide condemnation.