King Juan Carlos and Prime Minister Jose Luis Rodriguez Zapatero will formally unveil the new modernist extension designed by architect Rafael Moneo on Oct. 30 with the first show - "Modern Masters: The Prado's 19th-Century Masters" opening the next day.
To help celebrate the event, entry to the Madrid museum will be free of charge between Oct. 31 and Nov. 4. After that, there will be no charge for people visiting the museum between 6-8 p.m. Tuesday to Saturday and 5-8 p.m. on Sundays. The Prado is closed on Mondays.
Until now the museum has been free all day Sunday.
"The idea is to widen the free entry times and avoid the great amount of tension that built up on Sundays with so many visitors," Prado director Miguel Zugaza told Europa Press news agency.
The entry price to the museum at other times will remain at Ђ6 (US$8.50), which the museum said was one of the cheapest in Europe.
Other shows announced for this season include one beginning Nov. 20 of some 50 works by Velazquez, which is expected to include the National Gallery of London's "Venus at her Mirror."
In 2008, it plans a show on Goya in April and a major summer exhibit of Renaissance portraits.
The Moneo annex adds 17,000 square meters (183,000 square feet) to the 29,000-square-meter (312,000-square-foot) museum, considered to have the world's richest store of pre-20th-century masters, including Velazquez, Rubens, El Greco and Goya.
It features 1,400 square meters (15,070 square feet) of temporary exhibition space and print and drawings rooms that will allow the gallery to display 1,000 Goya prints that are currently in storage. The extension also frees up 40 rooms in the museum's original building.
Madrid's Thyssen-Bornemisza and Reina Sofia museums also have recently completed extensions. The three museums are within 10 minutes' walk of each other, along the central Paseo del Prado boulevard.