Some of the covers come from musicians — Beck, James Murphy of LCD Soundsystem, Mountains, High Places, No Age, Lucky Dragons — but some are spoken word, some simply recitations by actors.
He would introduce the drum, he said, and ask children to guess where its skin cover came from.
This performance of the Velvet Underground, which Bowie later covered, comes from Bowie's fiftieth birthday celebration in 1997.
The ideas for what to cover came from the stations themselves, said Patricia Harrison, the president and chief executive of the corporation.
The four photographs that make up the cover come from her "Chants to Nature" series, and she admires how they were used.
The idea for the cover came from a photograph Anderson's wife took of a homeless man on Thames Embankment, and Anderson later felt it would have been better to have used the photograph rather than commission the painting.
Ament said that the cover came from the idea on "how cool to have a yield sign where there's nothing to yield to", and the place was a road on the way to his Montana home which he considered perfect for the photo.
The untitled contemporary batik displayed on this month's cover came from a street market in Maputo, Mozambique, in April 2012.
The folio on this month's cover comes from the Bhagavata Purana, a celebrated text in Hindu sacred literature recited daily by millions.
The detail on this month's cover comes from a black-figured amphora, a ceramic vase popular in ancient Athens in the 6th century BC.
