An estimated four hundred gold records have been recorded in the Muscle Shoals area. Many of those are thanks to Muscle Shoals Sound Studio and the Muscle Shoals Rhythm Section, dubbed ``the Swampers.`` Some of the greatest names in rock, R&B and blues laid tracks in the original, iconic concrete-block building--the likes of Cher, Lynyrd Skynyrd, the Rolling Stones and the Black Keys. The National Register of Historic Places now recognizes that building, where Lynyrd Skynyrd recorded the original version of ``Free Bird`` and the Rolling Stones wrote ``Brown Sugar`` and ``Wild Horses.`` By combing through decades of articles and music reviews related to Muscle Shoals Sound, music writer Carla Jean Whitley reconstructs the fascinating history of how the Alabama studio created a sound that reverberates across generations.