A series of official photos released by the Grand Ducal Palace on Monday showed the government, as well as ambassadors to countries including the UK, Ireland and the US, paying their final respects to Grand Duke Jean, who reigned for 36 years.
He died on 23 April 2019 at the age of 98.
Members of the public may also pay respects until Friday or sign one of several books of condolence.
The state funeral will be held on 4 May.