How do I get the Princess?

I'm playing the old Super Mario Bros for the NES for the first time, and I keep getting to the castle with Bowser. However, every time I beat him, I don't get the Princess and instead just get Toad, and then sent out again.

I've tried a bunch of things - killing Bowser by spitting fireballs until he falls off, grabbing the hammer to break the bridge, but nothing seems to work. How do I get the princess?

Solution 1:

Defeat Bowser on world 8-4 to rescue the princess.

Solution 2:

If you look carefully, you'll notice Toad talking to you (Mario), telling you that the Princess is, in fact, located in another castle.

Thank you Mario!

But our Princess is in another castle!

There are 8 worlds in Super Mario Bros., each containing 4 levels, the 4th invariably being a castle. As luck would have it, the Princess is located in the castle of the 8th world, known as level 8-4.
After defeating Bowser in that castle, you will finally find the Princess.

Thank you Mario!

Your quest is over.
We present you a new quest.

Push button B to select a world