"3 Boroughs," for example, is a literal geography lesson, scratching out vocal samples that detail hip-hop's roots in Manhattan, Brooklyn and Queens, while simultaneously paying tribute to the birthplace of the X-ecutioners' members. On "A Journey Into Sound," Swift bends pitches live while beatboxer Kenny Muhammed spits drum and vocal samples. Even if the ear cares to apply musical dissection, it's almost impossible to determine where turntables end and vocal cords begin.

If recent trends have proven that rock bands can rap (can they?), hip-hop acts have been slightly less successful at getting their rock on. (Witness Ice-T's tepid "Body Count" or, if you dare, Canibus' "Rip Rock" and Mos Def's "Rock and Roll.") "Let It Bang" dispels that notion completely, pairing the X-ecutioners with hip-hop's greatest accidental rock group, M.O.P. The track is a full sonic beat-down, with guitars, drums, gritty vocals and scratches flying like loose fists. It works twice as hard as the album's legitimate rock collaborations with Everlast ("B-Boy Punk Rock 2001") and Linkin Park (returning a favor on "It's Goin' Down").

Other collaborations include Pharaoh Monch, Xzibit, Inspectah Deck, and Mad Skills on "Y'all Know the Name," and hip-hop futurist Dan "The Automator" Nakamura ("X-ecutioners [Theme] Song"). The most interesting pairing, however, is the scratch reconstruction of the Tom Tom Club's highly influential "Genius of Love," featuring new vocals by Tina Weymouth.

Tracks like "Genius," as well as the remake of Marley Marl's "Marley Scratch" and the Whiz Kids' "Play That Beat," contribute an important lesson in the hip-hop continuum traced on Built From Scratch. Hip-hop is built on its past, and no matter how much the art form evolves or how many MCs boast otherwise, serious turntablists such as the X-ecutioners know that where you come from is just as important as where you're at.