Which flags get to fly at Antwerp City Hall?

Today is the National Holiday of Belgium. On 21 July 1831, Prince Leopold of Saxe-Coburg and Gotha took the constitutional oath to become King of the Belgians. But I want to look at something else. 

Europeans visit other European countries over 7 nights on average

In the COVID-19 pandemic stricken year of 2021, tourism trips made by residents of the European Union to another EU Member State had an average duration longer than one week – 7.9 nights – ranging from 4.3 nights for trips to Czechia and Luxembourg to 11.3 nights for trips to Romania.