Read our feature PLAYBILL PICKS: Timeless Love Affairs on Stage.

Collaborating with composer Leonard Bernstein, playwright Arthur Laurents and director-choreographer Jerome Robbins on West Side Story, the contemporary adaptation of Romeo and Juliet, Sondheim set our hearts shooting sparks into space with the lyrics:

Today, the world was just an address
A place for me to live in
No better than all right

But here you are
And what was just a world is a star
Tonight

The obsessive Fosca offers one of the simplest expressions of love to the object of her affection, Giorgio, in the 1994 musical Passion.

Once titled Wise Guys, and later Bounce, the Sondheim musical Road Show – about the eccentric Mizner brothers – at last premiered in its final form at the Public Theater in 2008. Here, on disc, Claybourne Elder and Alexander Gemignani, as Hollis Bessemer and Addison Mizner, offer "The Best Thing That Ever Has Happened."

Shortly after his arrival in London, the young sailor Anthony Hope spies Judge Turpin's ward, Johanna, in her window. Immediately taken with the young woman, he expresses his love in the street below. Nathan Gunn performs the song "Johanna" in concert.

Another Sondheim love song that uses a woman's name for its title: "Maria." Tony, wandering the streets of New York City, sings of his love for the girl he just met. Leonard Bernstein conducts the song, performed by José Carreras.

The 1957 musical Gypsy, about a domineering stage mother and the daughters she thrusts into the spotlight, is better known for its central female star turn than its for on-stage romance. Here, the insistent Rose (as played by Patti LuPone) and Herbie (played by Boyd Gaines) share a tender and comedic moment in "You'll Never Get Away from Me."

The unlikely love song "Unworthy of Your Love" hails from Sondheim and James Weidman's 1990 musical Assassins. Written for the characters of John Hinckley (pining for Jodi Foster) and Lynette "Squeaky" Fromme (pining for Charles Manson), here are John Barrowman and Ruthie Henshall performing the song.

In Follies, Sondheim and James Goldman place past, present, memory and reality side by side, as once-lovers Sally and Ben imagine what was and what could have been in "Too Many Mornings." Here, Barbara Cook and George Hearn perform the song in the 1985 Philharmonic concert.

Performed by original cast member Dorothy Collins, "Losing My Mind" is as torchy as it gets. Sally's ode to Ben in the "Follies" sequence of the 1971 musical Follies.

Performed twice in the 1981 reverse-ordered musical Merrily We Roll Along, "Not a Day Goes By" is, at first pass, a song of rue and longing performed by Beth during her divorce proceedings from Franklin Shepard, and later, as we see the couple at their wedding, a song of hope and promise, while the lovelorn Mary looks on.

Bernadette Peters offers the "torch" version:

A look at the London revival, as "Not a Day Goes By" is performed during the marriage vows of Franklin and Beth:

Is it a stretch to call "Send in the Clowns" a love song? We had to include the gem from A Little Night Music, about mismatched and elusive love in all its forms. Judi Dench delivers a heartfelt rendition.

Here, original Broadway stars Glynis Johns and Len Cariou perform the original version and the reprise of the ballad, as the lovers find their proper pairing.

"So Many People," from Sondheim's early musical Saturday Night (originally set to premiere on Broadway during the 1954-55 season), was at last presented when Second Stage Theatre staged the production in 2000. Here, Laura Benanti performs the tender ballad during "Sondheim!: The Birthday Concert."

It may not be a proper love song, but the 1970 musical Company ends with Bobby, finally ready for love, performing "Being Alive." Here's original cast member Dean Jones recording the Broadway cast album.

In Sunday in the Park With George Dot returns as a vision to the young artist George, encouraging him to pursue his work and "give us more to see." Their duet "Move On" proves that love can span centuries: "We've always belonged together."

Bernadette Peters and Mandy Patinkin in the original production:

Bernadette Peters and Mandy Patinkin reunite for "Sondheim! The Birthday Concert."

Passion opens with lovers Clara and Giorio in bed, sharing so much "Happiness."