In December 1990, U2 had entered the recording studio in Berlin to begin writing songs for what would become Achtung Baby. The band recorded their jam sessions and sent the results to producer Brian Eno for feedback. One set of DAT working tapes was stolen and widely bootlegged around April 1991. This three-CD set is the most comprehensive collection of the band's sessions and is considered the holy grail of unofficial U2 material. (A word of caution: these are not even demos, much less rough mixes of the final album.) The Achtung Baby Sessions are valuable because they reflect U2's recording process on one of the 1990s' most important albums. This set is not U2 unplugged; most moderate fans would find the sessions maddening. But hardcore fans will gain a new appreciation for the band's creativity. These sessions represent no more than four months of the band's reinvention, once described as "The sound of four men chopping down The Joshua Tree." These three CDs capture the process -- described as thorough and effective once completed -- in midstream. If Achtung Baby is the album that completely changed U2's sound and style, then The Achtung Baby Sessions demonstrate the effort it took to get there. From April 1991 to February 1992, The Achtung Baby Sessions were released in four different formats. The first three pressings were on vinyl and were called The New U2: Rehearsals and Full Versions. February 1992 saw the definitive release of a three-CD set, called Salome: The Achtung Baby Sessions. The digital quality, of course, makes the vinyl versions useless to all but the most obsessive, completist U2 fans. "Salome" refers to the initial song that U2 based most of its early riffing and improvising on. The track was left off the official Achtung Baby release, but was included as a B-side on the "Even Better Than the Real Thing" single, which is a required purchase for owners of this bootleg. In the pre-Napster world, U2 became the first band to have a major release bootlegged before the project was released or abandoned. As a result, Salome: The Achtung Baby Sessions ranks up there with the Beach Boys' Smile and Prince's The Black Album for mythical bootlegs. U2 and their management both criticized the manufacturers of The Achtung Baby Sessions for cheating fans by selling inferior material. They claimed the final album evolved greatly from these sessions. But that is why they are important. Instead of compiling alternate versions of now-famous songs, The Achtung Baby Sessions reveal the often secretive songwriting process. Bono himself admitted buying a copy of the three-CD set. What follows is an overview of what nuggets are in The Achtung Baby Sessions. Achtung Baby titles are used when possible. Throughout the three discs, and especially with the first, Bono leads the recording process, directing the improvising band. The band was trying to tease hooks and powerful elements out of the ether -- to recreate what U2 meant right there in the studio. The songs on the album did not begin as separate compositions. Rather, they were inspirations jumbled together, and when U2 liked an element, they isolated it and later developed them into songs. (If this one fact -- and that you get to hear them do it -- does not give you chills, then The Achtung Baby Sessions are not for you.) It is fitting that the set starts with "Salome," the track U2 was finessing most during this early period. Track one is most similar to the released "Salome." Note the appearance of the "Zoo Station" bassline. The two songs are twins, but this version experiments with lyrics ("Deep in the houses of love" and "Got to get together"). It is clear, from the beginning, that U2 had predetermined Achtung Baby's themes and motifs. Disc one has another abandoned song that appears on the "Even Better Than the Real Thing" single: "Where Did It All Go Wrong?" (tracks two, three). The left speakers showcase some of the Edge's noodling, which sounds like "Mysterious Ways." Tracks four and five (with fan titles "Heaven and Hell" and "Doctor, Doctor," respectively) are both backed by the same instrumental but are meant to be different songs. The soulful qualities of "Heaven and Hell" should remind the listener of "Wild Honey" from All That You Can't Leave Behind. Track six is based around the guitar riff from "The Fly" and showcases a high falsetto used throughout the finished album. The numerous reworkings of "Salome" continue with tracks seven and eight. Early in track seven, Bono gives Larry Mullen comments and later Edge jumps in with the familiar riff from "Zoo Station." Track eight is where some of the atmosphere (loops, bells, etc.) found on Achtung Baby makes it into the sessions. The instrumental flourishes found in "Sunset in Colors" (the first part of track nine, sounding a bit like Lou Reed's "Sweet Jane") influenced U2's live performance of "Running to Stand Still" during the various Achtung Baby tours. Tracks nine (part two) and 11 are early workings of "Until the End of the World" (fans call these two early versions "Chances Away" because of the lyrics). The final track on disc one is the most complete version of "Until the End of the World," with a little Cream influence ("I feel free..."). The guitar riff that was mostly used in the chorus of previous versions is heard here from beginning to end. Disc two focuses on some of Achtung Baby's big singles and thankfully has not one version of "Salome." Track one is a looser (and clearly earlier) version of "Until the End of the World." The lyrics in this demo show that the aggressive song on Achtung Baby had a more vulnerable beginning: "Where did you go? I'd really like to know." Track two, called "Sweet Baby Jane" by fans, is another abandoned original. It is refreshing to learn that not everything U2 writes is brilliant. Track seven is a straight instrumental version of "Even Better Than the Real Thing," which will be a treat for the single-buying U2 fans. Tracks three and four are early acoustic versions of "Who's Gonna Ride Your Wild Horses," and diehards will enjoy some alternative lyrics. Tracks eight, nine, and 11 are called "She's Gonna Turn Your Head Around" by fans and have more fun noodling by Bono and the guys. Track ten is a jamming "So Cruel," where Bono is trying out (or coming up with) lyrics while the band plays a slowed-down version. Tracks six and 12, with the fan title "Take Today," are some of the more distinct tracks in this whole set, with horns and harmonicas throughout. Though first written in 1990, this demo becomes "North and South of the River" and appears on the single for "Staring at the Sun" (1997). By disc three, most listeners will be tired of listening to U2's process. This might be a good time for a break, because there are some valuable tracks still to come. In fact, disc three might have the most in common with the finished Achtung Baby. "Someone" (track one) is one of the best snippets of an abandoned song in the whole collection. An early version of "So Cruel" (track two) has the percussive and lyrical elements (love and lust) of the album version. "Acrobat" (track three) is very far along, but as with every Bono composition, the lyrics are unfinished. The line "How does it feel to be burned by the sun" might have been the early seed for Pop's "Staring at the Sun," but that might also be a stretch. If you haven't guessed by now, such guessing is the fun of The Achtung Baby Sessions. Disc three has more "Salome" than anyone could possibly want (tracks three, and eight to 12) with the band experimenting on overdubs and chord progressions. Clearly this was a valuable process for U2, but it's excruciating for the listener. It makes you wonder how much of this material Brian Eno could have the stomached. Skip the "Salomes" or make your own smaller selection of the best tracks. Track six is a standout of the set. It has dizzying elements of "Lady With the Spinning Head," "Ultraviolet (Light My Way)," and "The Fly." Fans call this song "Take You Down" because of the lyrical refrain here. It is interesting to hear how two songs that made it onto Achtung Baby and one of the better B-sides from the "One" single all have their beginning in the same demo. "Going Down South" is the last new song on The Achtung Baby Sessions and sounds instantly familiar. Maybe because after over three hours you feel like you are in the studio with U2. That feeling is the reason to own The Achtung Baby Sessions. These are not CDs for everyone. Even U2 aficionados will only want to dust these off every five years or so. But they do reveal a tremendously gifted band whose studio skills are often overlooked in the press. When Brian Wilson authorized the release of The Pet Sounds Sessions in 1997, it raised the question if other bands might do the same in the years to come. It would be nice to hear more working mixes, alternate takes, and rarities from other U2 records. Hopefully serious fans won't have to wait 30 years.