The Doors' second album, released a little more than eight months after their debut, follows a similar pattern: a few acid-spiked pop songs, the occasional blues influence, an epic closing track. But the release of the Beatles' landmark 'Sgt. Pepper's Lonely Hearts Club Band' between the two records inspired the Doors to experiment with noises on 'Strange Days.' The result is their most psychedelic album, a playground of sounds wrapped up in the moment of 1967.

The Grateful Dead were at the forefront of the San Francisco psychedelic scene; their 1968 album 'Anthem of the Sun' was assembled as a sound collage and boldly explored the genre's wide-open possibilities. But their psych masterwork captures the band in its element onstage. This LP's improvised moments point toward the Dead's lucrative future, but it's the holes they fill on songs like the positively trippy "Dark Star" (clocking in at 23 minutes here) that define their formative era.

released just seven months after 'Are You Experienced' – is both more uniform and less straightforward than the debut, with the Experience taking their psychedelic experiments in exciting new directions. The side closers ("If Six Was Nine" and "Bold as Love," respectively) are the obvious ringers, but even the two-and-a-half-minute ballad "Little Wing" takes on period textures. Hendrix hated the LP cover, but the music inside pretty much delivers on its messy kaleidoscopic explosion.

Before they became one of the biggest bands on the planet with prog-leaning epics like 'The Dark Side of the Moon' and 'The Wall,' Pink Floyd were an unstructured, but no less ambitious, psych-rock group with songs about depressed scarecrows and wine-sipping gnomes. 'The Piper at the Gates of Dawn' was the only full album they made with original leader Syd Barrett before he was forced out due to increasingly erratic behavior. The 10-minute "Interstellar Overdrive" is a genre highlight, but the entire LP is a psych-rock milestone.

The Beatles' Summer of Love masterpiece is a lot of things: pop-music landmark, art-rock milestone ... but it's also the record that helped bring psychedelic music to the mainstream, even if its dips into the genre appear more subtle on the surface. All of the hallmarks are here, however, from mind-altering studio effects to songs with double meanings (the debate over "Lucy in the Sky With Diamonds" continues to this day). It's also an accessible work that's druggy, deep, playful, and wildly ambitious all at once.

One record of this two-LP set was recorded live. The other includes some of Cream's most innovative music. The band worked for months on the sessions with producer Felix Pappalardi, who guided Eric Clapton, Jack Bruce, and Ginger Baker through songs like "White Room" and "Pressed Rat and Warthog," twisting their electric blues and folk into something less familiar. 'Disraeli Gears' is the band's definitive psychedelic statement, but they often venture further out there on 'Wheels of Fire.'

Jefferson Airplane's classic lineup came together on their second album with the addition of singer Grace Slick and drummer Spencer Dryden. Recorded over the final months of 1966, 'Surrealistic Pillow' was one of the first psychedelic albums to break into the mainstream (it reached No. 3 upon release in February 1967) while introducing counterculture notions (like the head-feeding pills of "White Rabbit") to a new, eager audience. The San Francisco psych scene pretty much begins here.

The 13th Floor Elevators were as much a garage-rock band as a psychedelic one, maybe even more so. But their debut LP was one of the first to embrace the title. Like Pink Floyd founder Syd Barrett, Elevators' frontman Roky Erickson embraced the lifestyle he sang about. He ended up in a psychiatric hospital in his native Texas and underwent shock therapy. Unlike Barrett, Erickson continued to make music until his 2019 death. 'The Psychedelic Sounds of the 13th Floor Elevators' is his masterwork, all fuzz guitar, electric jug, and gurgling sound effects.

The Byrds had already dipped into psychedelic music on their previous album, 'Fifth Dimension,' which included the groundbreaking "Eight Miles High." Their fourth album got even deeper. There are still remnants of the band's past on 'Younger Than Yesterday': a Bob Dylan cover ("My Back Pages"), some crisp folk-rock ("Have You Seen Her Face"). But there's also a more grown-up reflection of the world around them, in both the music and lyrics. "So, You Want to Be a Rock 'n' Roll Star" was the hit, but songs like "C.T.A.-102" offer a round-trip ticket to new lands.

Before long, psychedelic music found its way into corners of the world where popular Western styles previously had little impact. Os Mutantes were part of Brazil's Tropicalia scene, which fused local and African rhythms with American pop and psychedelia. The result was a splintered path that explored exciting new territories and shades in the music. Some great records came from the scene; Os Mutantes' self-titled debut contains the most mind-widening trip of the bunch.