Im turning 15. birthday ideas in Philadelphia?

Im turning 15, i have one group of friend from my old school and one from me new, i cant mix the 2 groups (they dont get along) so i am having the old school group come over for a house party, but the new school.. im aloud to take them somewhere and do something. any suggestions, i hate bowling and roller skating. so lets stay away from those ideas. lol. The birthdays comin up in a few weeks, so it has to be something fun for the chilly weather. Or inside. Thanks in advance for your idea =]]