Apollo astronauts left 50 tons of litter on the moon, plus six vehicles.

Since NASA's iconic mission Apollo 11, which marked the first human landing
on the moon in 1969, there have been six other Apollo missions to the moon.
Except for Apollo 13, which had to make a quick emergency return, two
astronauts landed on the moon in each of the Apollo missions 11-17. The
last Apollo mission was completed in 1972 and as of 2015, no human has set
foot on the moon since then. There have been however numerous probes,
unmanned robots and rockets sent to the moon.