Every April 23rd on the day of Sant Jordi, or St George, people in the wealthy northeastern region give each other a rose or a book in a celebration of love and culture.
Originally the tradition involved men giving their love a rose, while she in return would give him a book. But it has evolved and today women also receive books and flowers are given as well to mothers, daughters, friends and even co-workers.
Throngs of people browsed book and flower stands in the Catalan capital's historic heart under a bright blue sky, in a scene repeated in cities and towns across the region.
"It's a special day. All the streets are decorated with flowers and books, its very beautiful," said Joan Redon, 39, a computer technician as he made his way along Barcelona's packed Las Ramblas boulevard with his girlfriend, who carried a red rose he gave her earlier.
"There isn't anyone in Catalonia who doesn't follow the tradition," he added.
Retailers expect to sell six million roses, and over 1.5 million books, on Sunday alone in Catalonia, which is home to 7.5 million people.
Catalan booksellers make 5-8 percent of their annual sales on the day of Sant Jordi - which is also St George's Day in Britain - said the secretary of the Catalan booksellers association, Maria Marin.
"It's impressive," she said.
Musicians performed in the streets of Barcelona, adding to the festive mood while authors signed copies of their books in booths set up for the day.
Best-selling Irish novelist Marion Keyes was among the big names signing books this year.
Catalonia adopted St George as its patron saint in the 15th century.
According to legend he saved a princess by killing a dragon with his spear while riding on a white horse. The dragon's blood caused a rosebush to grow and he offered one of its roses to the princess.
Since 1931 a book fair has been held in Barcelona on April 23rd - St George Day and the anniversary of the burial in 1616 of Spanish writer Miguel de Cervantes, the author of "Don Quixote".
Since then the tradition of offering books and roses in Catalonia on that date has thrived, even during the 1939-74 dictatorship of General Francisco Franco when the open sale of books in the Catalan language was banned.
The tradition is sparking growing interest abroad. This year a delegation came from China to observe the event with a view to repeating it in the Asian country.
"I'm very impressed. It's a unique event in the whole world I think," said Andrea Edel, who is responsible for culture in the southwestern German town of Heidelberg.
The Catalan Book Chamber plans to ask that the United Nations Educational, Scientific and Cultural Organization (UNESCO) include the tradition on its "intangible world heritage" list.
"It meets all the criteria. It has existed for a long time, it is the expression of a specific culture and it has a future," said the president of the chamber, Antoni Daura.
The initiative is backed by the regional government of Catalonia as well as the central government in Madrid, a rare example of cooperation between the two sides at a time of high tension over the Catalan government's push for independence for Catalonia.
"Sant Jordi transcends politics. It's a festival of feelings and culture, it is something universal," said Tixis.
By Daniel Bosque