More than 500 guests attended the big event.
Former king took up residence in Abu Dhabi in August 2020
The ex-King travelled to London last month to attend the funeral of Her Majesty Queen Elizabeth a move which led to an outcry in Spain because of his self-imposed exile.
Once revered for his role in Spain's transition to democracy, the popularity of Juan Carlos fell drastically amid financial scandals and public disgust at an elephant-hunting trip to Africa.
"King Juan Carlos was suspected of tax fraud...."
Archive image of former king, Juan Carlos, and the Queen Mother, Sofia, during a sitting of Spain's Congress.
"Interview took place on Mallorca in the early 1990s..."
Juan Carlos was greeted by Infanta Elena.
King Felipe with his father - (Archive image).
Spain's former King Juan Carlos leaves after attending the funeral ceremony of Luxembourg's Grand Duke Jean at the Notre-Dame Cathedral in Luxembourg, May 4, 2019.
Juan Carlos is currently in the UAE.
The matter relates to the period 2016 to 2018, when the ex-king no longer had "inviolability".
On Friday that Juan Carlos had travelled by private plane from Spain to the United Arab Emirates on Monday.
Interview with historian Paul Preston CBE, biographer of Franco and the former King of Spain Juan Carlos, and considered one of the greatest experts on the Civil War and modern Spain.