A collection of correspondence and mementos chronicling the relationship between Leonard Cohen and his muse, Marianne Ihlen, has been sold for nearly $1.2 million.

The Christie's online sale, which closed Thursday, featured more than 50 letters from Cohen to Ihlen, who inspired his 1967 song "So Long, Marianne," as well as photographs, postcards and personal items.

A centuries-old bronze bell that adorned the home Cohen and Ihlen shared on the Greek island of Hydra in their 20s led the auction with a winning bid of nearly $110,000.

According to Christie's, the bell, which is conspicuously cracked, is believed to have inspired Cohen's famous lyric in "Anthem": "Ring the bells that still can ring. Forget your perfect offering. There is a crack, a crack in everything. That's how the light gets in."

Many of the letters exceeded their pre-auction estimates several times over, including a top-selling 1960 missive from Montreal that fetched more than $75,000.

In the typewritten note, Cohen tells Ihlen about his ambivalent feelings for his hometown.

"At first I hated Montreal. It seemed little, cold and brutal," he writes. "But now I feel a lot better. I have rediscovered my favourite streets and iron fences.

"I burn wood in the fireplace and think how much we would enjoy being here together."

The exchanges offer a personal glimpse into Cohen's trajectory from struggling young poet to famous singer-songwriter, tracking his enduring connection with Norwegian-born Ihlen from the early days of their 1960s love affair through the late 1970s.

In August 2016, Cohen's official Facebook page posted a tribute to Ihlen after her death at age 81. Ihlen's close friend and documentarian Jan Christian Mollestad posted to the page thanking the singer for a letter he sent in her last days.

"Your letter came when she still could talk and laugh in full consciousness. When we read it aloud, she smiled as only Marianne can," Mollestad wrote.

Cohen died a few months later in November 2016 at the age of 82.