That is not so easy to identify because of the following.
The band has sold over 200 million albums worldwide, including 111.5 million certified units in the United States and they have had all of their original studio albums reach the top 10 of the Billboard album chart in the U.S., with six reaching the number one spot. (Wikipedia)
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*IMPROVE*
Honestly the greatest hit is stairway to heaven, i do not know a single person who has not heard that song at least once in their life
"stair way to heaven" is the only good song they ever wrote
The biggest Zep song hands down is stairway to heaven, its one of the few known by all music listeners no matter what Genre you are mainly into.
The main singer of led zepplin is Robert Plant
CBS Records
8 minutes and 2 seconds.
Most of their hits were late 1969-1975
On itunes, you can buy the complete Led Zeppelin set with all of their albums for $99.99
how big is a zeppelins
Their last studio album was "In Through The Out Door"; their last album was Coda.
Nickelback has stated that they got much of their inspiration from Led Zeppelin. Before becoming famous, they performed cover songs of Led Zeppelins music.
Oh let the sun beat down upon my face, stars to fill my dream
Although their "greatest hit" is arguable, more than likely it was off Led Zeppelin 4, otherwise known as Zoso. Zoso included "Stairway to heaven", "Black Dog", and many others.