What kind of building was the “bastille” before it was stormed?

Hi !!

Before it was stormed the "Bastille" was a fortress known as the "Bastille Saint Antoine".

It used to be a state prison for the kings of France

Formerly it was called "Fort et Bastide Saint Antoine lez Paris" (built between 1356 and 1358) .I'm sorry, my English is too poor to explain what 'bastide' means.. but the word 'Bastille' is derived from it. A 'bastide' is a mansion in south of France or an element of a fortification. So it was just a small castle with two towers.

In 1367 the king Charles VII decided to build fotifications around it to make  a real castle with walls around it and eight towers.

The story is quite long

When Louis XI became king of France, it began to be occasionnally a prison.
Le cardinal de Richelieu officially turned it into a jail around 1600.

well anyway, before it was stormed, La Bastille was a fortress and was used as a prison

Hope this will help :)