<human>:  Where did Alexander Fleming discover Penicillin?
<bot>: Alexander Fleming discovered penicillin in a lab in the UK. He noticed that mold growing on some Petri dishes had killed bacteria on them. He knew that mold was made up of cells, so he figured that the mold must have been killing the bacteria by producing a chemical. He tested this theory and found that the mold was indeed producing a chemical that killed bacteria. This chemical was later named penicillin.