led zeppelin never released an album
although the group was initially unpopular with critics  they achieved significant commercial success with albums such as led zeppelin lrb 1969 rrb  led zeppelin ii lrb 1969 rrb  led zeppelin iii lrb 1970 rrb  led zeppelin iv lrb 1971 rrb  houses of the holy lrb 1973 rrb  and physical graffiti lrb 1975 rrb