BBeckhamRomeo0904_01_X17.jpgVBeckham090408_03_X17.jpgYou only turn six once - and if you're Romeo Beckham, you do it in style!

Universal CityWalk played host to one heck of a costume party yesterday, as Victoria escorted the birthday boy (in the adorable Batman costume) and his little brother Cruz around the park, buying balloons and taking in all the sights and sounds. Happy birthday, little guy!

And wait 'til you see the guest list for Romeo's party - seriously, this is probably the hottest lineup of guests we've seen since, well, Vicky's 34th a few months back!

VBeckham090408_02_X17.jpgGavin Rossdale and Kingston were on hand to send Romeo their birthday wishes. Our videographer tried to get Gavin to go on the record about the VMAs, but the rocker was too busy having fun with his son. Unfortunately, it looks like Kingston had already gotten tired of his costume by the time we spotted him - too bad, he must have looked adorable!

Victoria Beckham BBeckhamRomeo0904_13_X17.jpgHeidi Klum's daughter Leni, on the other hand, wasn't shy at all about being seen in her costume - and why should she be? She looked as pretty as a princess! (Heidi also brought her son Henry, although the little tyke spent most of the day hanging back from his famous mommy. You can still see him all dressed up in his costume on the far left of the group photo above, though - too cute, huh?)