Where do I fight Hydra?

Excuse me, I'm a bit confused about something. The information I've been given mentions fighting against Hydra, but I'm not sure where exactly I should be engaging in this battle. Could you please clarify for me? Is there a specific location or platform where I need to go to confront Hydra? I'm eager to take on this challenge, but I just want to make sure I'm heading in the right direction. Any guidance you could provide would be greatly appreciated.