The most famous Mahatma definitely indicates** Mahatma Gandhi** and it was written that he was permanently brought which means that his **statue** was brought to lisbon.
Looking at the pictures of the Statue shows the year of the statue inaugaration in **1998**.
Using the list of Lisbon Mayors from Wikipedia, the mayor in Lisbon during this time was **João Soares**.

Hence the **flag{João Soares}**