The much anticipated Festival Imperial finally kicked off Saturday in front of thousands of music fans at La Guácima near Alajuela, northwest of the Costa Rican capital, San José.

With approximately 46,000 people expected over the course of the two-day festival, the event is one of the biggest ever held in Costa Rica, and follows the sell-out success of a concert by metal icons Iron Maiden at the Ricardo Saprissa Stadium in February.

An ensemble of musicians from several Costa Rican bands opened the festival on Saturday, singing a variety of hits from the country's rock scene. This was followed up by a performance from homegrown group Le*Pop, who told reporters that they were “very happy and excited” to be performing at the festival. These bands braved the onslaught of a host of big acts from abroad.

Grammy-award-winning Mexican group Café Tacvba, who came up next, was well received by the enthusiastic crowd. Café was followed by Argentineans Babasónicos, promoting their new album “Mucho.” The first single from the album, called “Pijamas,” was released April 7.

However, there was no doubting that the final two acts, Californian group Incubus and Chicago-based rockers Smashing Pumpkins, were the two most eagerly anticipated performances.

Incubus played first, performing some of their best-known tracks such as “Nice to Know You” and “Are you In?,” from the album “Morning View,” alongside newer tunes such as “Anna Molly” from their latest album, “Light Grenades.” A particular highlight was their classic track "Drive," which had vast swathes of the crowd singing along.

“Thank You, Costa Rica!” screamed charismatic frontman Brandon Boyd.

Smashing Pumpkins frontman Billy Corgan, dressed in a striking layered silver skirt, was similarly willing to engage with his audience during a long set, which featured the hits “Today,” “Ava Adore” and “1979.”

“It is very nice to be here for the first time,” said Corgan. “It only took us 20 f---ing years to get here.”

Reaction from fans was overwhelmingly positive. “I hadn't really heard of any of the Spanish bands, apart from Café Tacvba,” said Brittney Barker, 20, a student from Tennessee on exchange in the country. “But I thought they were pretty good. And I really, really loved Incubus,” she said.

“Incubus were very good,” agreed a local fan, Sebastian Loaiza, 21, adding, “although it was quite a short set.”

“To be honest I just came to see Smashing Pumpkins,” admitted fellow Costa Rican Diana Mejías, 24.

The festival was set to continue after press time yesterday with performances by Costa Rican group PorPartes, Mexican alternative band Zoé as well as UK singer-songwriter Seal and Spanish-American pop star Enrique Iglesias. Headline British group Duran Duran, a 1980s rock icon, was scheduled to close the festival.