Building a 100 album vinyl collection 3 must have albums are?

Too many to count, so off the top of my head: Donald Fagen “The Nightfly”; The The, “Who’s Next”; Chicago, “Chicago Transit Authority.” Best wishes!

Big Head Todd -- Sister Sweetly 

Art Pepper -- Art Pepper Meets the Rhythm Section

Beethoven's Violin Concerto -- Anne Sophie Mutter

Led Zeppelin Physical Graffiti

The Beatles Abbey Road

The Doors LA Women

As usual, lots of great suggestions by some serious music lovers and audiophiles. 
Here are my 3. (Only 3!?!??!!)

1. Everly Brothers. A Date With The Everly Brothers. (Well recorded. Touching and emotional. Country and Blues crossover to equal Rock n Roll. One can hear where The Beatles, The Beachboys were influenced and “got” there sound. IMHO. 
 

2. A Clockwork Orange soundtrack. Well recorded. Excellent intro to Classical music for those of us who were not exposed much. 

3. Thelonious Monk, Talking Heads, Santana, Mozart…

Dylan, Blood on the Tracks (his best material & sonics)

Fleetwood Mac, Eponymous, 1975  (ditto)

Pink Floyd, Dark Side (material -- Floyd sonics are consistently fine)

Counting Crows, August and Everything After (abundance)

Neil Young, After The Gold Rush (abundance, emotional range)

Ramsey Lewis Trio, Pot Luck (a heaping platter of magic)
(Criteria: Appeal of material, arrangement/mix, sonics)