Monaco's twins celebrate their birthday with superhero party

Monaco's royal twins have celebrated their 4th birthday in the best way possible, welcoming comic book heroes into their palace.

Prince Jacques and Princess Gabriella were all smiles in a series of photos from their superhero party, shared by their mother Princess Charlene on Instagram.

The adorable twins were dressed for the occasion, with Prince Jacques wearing a Spider-Man jumper while the little Princess wore a party dress and a denim jacket featuring Mickey Mouse.

Their birthday cakes – they had several - were decorated with images of Spider-Man and Wonder Woman.

As you'd expect at a royal party, the cakes were extra special: chocolate with chocolate icing, and Monaco vanilla panna cotta decorated with fresh fruit.

Inside the palace, the royal family's private quarters were decked out with balloons, banners, party tables and streamers, all featuring the twins' favourite movie heroes including Superman, Batman and Frozen's Elsa and Anna.

A giant Spider-Man figure was seen hanging off the side of a building within the palace grounds.

There was a surprise in store for the birthday boy and girl when Monaco's Fire Department arrived with their cherry-picker. Jacques and Gabriella were allowed inside the cabin and given an aerial view of the palace courtyard, much to the amusement of their father Prince Albert.

"Such fun at our party! Thank you to our firemen for the surprise visit! Our True Heroes" Princess Charlene wrote on Instagram, alongside several photos from the event.

During the party, the twins were treated to a visit by several comic book heroes including Batman, Iron Man, the Hulk, and of course, Spider-Man who appears to be a favourite with the youngsters.