[5] The opening of the Expo on 1 May 2015 was marred by protests from anti-austerity activists, black bloc, and anarchists which caused criminal damage, resulting in the police using tear gas.

[6] As Vatican City invested €3 million to obtain its own pavilion at the event before his appointment to the papacy, Francis said that, although it is a good thing that the Church is involved in causes that battle hunger and promote cleaner energy, he stated that too much money was wasted on the Expo itself by Vatican City.

[8] On 22 March 2015, the incumbent mayor of Milan, Giuliano Pisapia, announced that he had chosen not to run for re-election in 2016 for a second term in office.

Following Pisapia's decision, the ruling center-left coalition decided to call an open primary election to choose a new single mayoral candidate.

On 11 March 2021, Sala joined the European Green Party, after years of political independence in the centre-left area.