Landmark Puerta del Sol square is decorated with festive lights in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

A child is seen at Puerta del Sol square in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

A child is seen at Puerta del Sol square in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

Kids are seen at Puerta del Sol square in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

A couple take a selfie at Puerta del Sol square in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

People enjoy themselves in an outdoor restaurant in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

Vehicles pass along a street decorated with festive lights in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

Vehicles pass along a street decorated with festive lights in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

People enjoy themselves in an outdoor restaurant in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)

A girl poses for a photo in Madrid, capital of Spain, Dec. 21, 2018. Christmas lights illuminate the main streets of Madrid, heralding the start of Christmas and New Year celebrations. (Xinhua/Guo Qiuda)