It was four years ago today (January 10th, 2016) that the world lost David Bowie, just two days after his 69th birthday. Bowie's death followed a private 18-month battle with cancer, and according to reports from insiders in the Bowie camp, the music legend died from liver cancer, after suffering from a handful heart attacks in recent years. Bowie was survived by his wife of 23 years, supermodel Iman, his son, movie director Duncan Jones, and his daughter with Iman, Alexandria.

2019 saw the release of previously unheard Bowie material, including a vinyl singles box set, titled, Spying Through A Keyholes (Demos And Unreleased Songs), featuring nine unheard demos and early takes from Bowie's late-'60s sessions.

In August, the new documentary, David Bowie: Finding Fame, debuted on Showtime, and delved into the rock icon's formative years that preceded his global superstardom.

Also released was the new two-LP version of the VH1 Storytellers collection. The set, which was recorded and filmed on August 23rd, 1999 at The Manhattan Center's Grand Ballroom in New York City, was issued in 2009 as a CD, DVD and digital download -- with the vinyl version featuring the late-icon's full set performed that night.

The latest Bowie box set, Conversation Piece, was released in November, and chronicled his work from 1968 and 1969. The collection features "home demos, BBC radio sessions, studio recordings with guitarist John "Hutch" Hutchinson, and the experimental music and mime group, Feathers." The set also celebrated the 50th anniversaries of the release of the "Space Oddity" single and Bowie's second album, David Bowie -- better known as Space Oddity.

The new box featured a brand new mix of the Space Oddity album by long-time Bowie producer and collaborator Tony Visconti. The album includes the title track of the boxed set, "Conversation Piece," restored to the track listing in its initially intended position before it was originally dropped due to time constraints of the vinyl.

Mattel toys released a new "Barbie as Bowie" doll, with Billboard reporting at the time, "the doll is dressed as the late superstar's extraterrestrial glam-rock alter ego, Ziggy Stardust, complete with his iconic striped metallic 'space suit' and platform red boots. The dramatic look is topped off with Ziggy's signature fiery-red hairdo and astral sphere forehead icon." The "Barbie as Bowie" doll sells for $50.

2018 saw the archival David Bowie Is exhibit open in March at New York City at the Brooklyn Museum for a four-month run. A new "augmented reality app" based on the multimedia museum exhibit was launched on January 8th, 2019. The app is narrated by Gary Oldman, with posting, "The app will allow users to interact with 'the show's hundreds of costumes, videos, handwritten lyrics, original works of art, and more.' A virtual reality David Bowie Is experience is also in the works.

Although tributes were literally non-stop in the days and weeks following Bowie's death, perhaps the most touching tribute was in July 2016 when Bowie's 1974 classic "Rebel Rebel" took on Herculean proportions when it was played in unison by over 1,000 musicians. A professionally filmed clip of the volunteer-based rock band dubbed Rockin' 1000 performed the song in Cesena, Italy's Orogel Stadium.

In 1983, David Bowie shed light on how and why the character of "Ziggy Stardust" came to exist: "I think I was quite happy to buy into the idea of reinvention, up until the beginning of the '80s, really. When I was a teenager, I had it in my mind that I would be a creator of musicals -- I sincerely wanted to write musicals for the West End and for Broadway, whatever. I didn't see much further than that -- as a writer. And I really had the idea in my head that people would do my songs. And I was not a natural performer; I didn't feel at ease onstage -- ever. And I had created this one character -- 'Ziggy Stardust' -- that it seemed that I would be the one who played him, because nobody else was doing my songs and the chance of my getting a musical mounted were very slim, and so, I became 'Ziggy Stardust' for that period."

David Bowie explained that his late-1970's work with producer Brian Eno forever shaped the way he thought about songs and music: "The whole idea of using a recording studio as an instrument, of not necessarily thinking that you have to be prepared totally before you go in; that accidents will happen and sometimes planned accidents work our really well. If there's a bad note, you can layer that note several times with other instruments and suddenly that bad note sounds like an extraordinary piece of arrangement."

Although David Bowie will always be best remembered for pushing the creative envelope, until the end he tried to bear witness and give a voice to the plight of the world he saw around him: "Some kind of statement or indictment of an uncaring society, or particularly the response to what's happening in terms of the homeless, people who are totally uncared for in terms of education or being fed properly, or housed properly. There's such a diversity of political stance, where the high powered authority seem to be far more concerned with their relations with Russia or the Middle East and the whole idea of what's happening at home, on the streets with the indigenous people seems to be swept under the carpet."

In 2003, Bowie spoke about mortality during a rare TV appearance on Britain's Parkinson talk show: (David Bowie): "I had this poetic, romantic, kind of juvenile idea that I would be dead by 30. 'Cause that's -- all artists think: 'I'll be dead by 30! Y'know, I'm going to get TB and die.' (Laughs) But you don't, y'know, you get past it and then suddenly, you're 30 and you're 40 and then you're 50 and 57, and then all that. And it's a new land, y'know?" (Parkinson): 'Sure." (Bowie): "I'm a pioneer -- me and my kind are just sort of scraping the edge of what this think is about, being a rock and roller at the age of 57. But my revenge is all these bands that are below us, they've got to do this -- so, they kind of say: 'Yeah, they're like, really old' -- but secretly they're thinking, 'I better watch how he does it, 'cause I'm gonna get there soon (laughter).'"