When you go to Joffre Street as part of the story in F.I.S.T Forged in Shadow Torch, you have a choice of two different locations to head towards. One is the Sewers, and the other is Arsenal. You can go to either one, it doesn't matter, but we suggest going to the Sewers.
We recommend the Sewers first because you get a new ability there called Omni-Dash. This allows you to dash diagonally and vertically, making movement a dream and allow you to reach places far easier. If you go to the Arsenal, you do not get any abilities at all, so you might as well get Omni-Dash to make the Arsenal that trad bit easier to get around.
By going to the Sewers first, you get one of the worst parts of the game out of the way because you have to do a few underwater segments where you have a limited supply of oxygen. They make it easier by using the Drill to go faster, but if it hits anything, you bounce off and waste a ton of time and breath, so it's more of a hassle.
But the Sewers is the hardest location of the two places. Omni-Dash is an awesome ability, but Arsenal is far easier.
Looking for more F.I.S.T. Forged in Shadow Torch guides? ProGameGuides has you covered!