Pierre Casiraghi
Pierre Casiraghi, son of Princess Caroline of Hanover, and his girlfriend Beatrice Borromeo arrive to attend a cocktail party with the Monegasque community at the Monaco Palace square to celebrate the tenth anniversary of the reign of Albert II in Monaco, July 11, 2015.REUTERS/Jean-Pierre Amet

With only a week left until his wedding to Italian aristocrat Beatrice Borromeo, Monaco's Pierre Casiraghi celebrated his last days of the single life with a group of friends at Requesens Castle, a ninth century fortress just north of Barcelona, for his bachelor party.

The weekend celebrations, which included his uncle Prince Albert, were organised by Casiraghi's friend Aldo Comas, according to Spanish newspaper La Vanguardia. Comas first met Casiraghi and his brother Andrea at the exclusive Collège Alpin International Beau Soleil of Switzerland.

Hello! Magazine reported that Comas was also a guest at Andrea Casiraghi's wedding to Tatiana Santo Domingo in 2014.

According to La Vanguardia, the festivities were held mostly at night, with Comas bringing in water and electric generators to provide light. The all male group arrived by horseback or drove in, the Spanish newspaper reported.

The lavish party included local Catalonian cuisine provided by La Cantina, a restaurant located near the castle. Several guests allegedly stayed at the Hotel Can Xiquet de Cantaloups, while another group stayed at Comas's home.

Casiraghi and his girlfriend are set to tie the knot in a civil ceremony in Monaco on 25 July before their lavish religious wedding in the bride's native Italy in August. As previously reported by IBTimes UK, the 27-year-old son of Princess Caroline of Monaco will marry his 29-year-old bride in the gardens of the Grimaldi palace.

The young royal proposed to the journalist and TV presenter with a pink diamond ring in 2014. The couple has been together since meeting at university in Milan in 2008. They will have their religious ceremony on 1 August in the Barromean Islands.