Conversation so far:
Where was Sigmund Freud born?
Sigismund Schlomo Freud was born to Jewish parents in the Moravian town of Freiberg, in the Austrian Empire.
When was Sigmund Freud born?
Sigismund Schlomo Freud was born on 6 May 1856.
Where did Sigmund Freud go to school?
In 1865, the nine-year-old Sigmund Freud entered the Leopoldstädter Kommunal-Realgymnasium, a prominent high school.

Question: what did he study?
Self-contained rewrite: What did Sigmund Freud study?