Refer to the passage below and then answer the question afterwards in the same language as the passage:

Passage: The origin of the fort goes back to the Sur dynasty, where emperor Sher Shah Suri ordered the court to be constructed after his victory over the Mughal emperor Humayun. Construction of the fort began in 1541. It was made primarily as a defense against the Gakkhars.

Question: When was the fort constructed?
1541