At the Gate of the Horn can be found on the 2-disc Tradition Masters compilation, but I really should focus on the now out-of-print original. Released in 1957, At the Gate of the Horn, a mix of traditional African-American spirituals and English folk songs, is thought to be Odetta's best.
I'm pretty sure I discovered Odetta by way of Bob Dylan (more about my relationship with Dylan's music here), and I fell in love with her deep, resonant voice. Born Odetta Holmes on New Year's Eve, 1930, Odetta is a singer-songwriter, activist and has been referred to as "The Voice of the Civil Rights Movement." (Wikipedia). She died two years ago, just before her 78th birthday.