A year ago I got a position at a bank as a Solution Architect. My job is to design the software and infrastructural architecture for large-scale ($1 million+) projects.
I did not have one particular mentor. I was essentially recruited out of a career of increasingly larger software development projects. My experience with a broad spectrum of full-lifecycle projects got me the job as an Architect. My current employer was looking for a background in software development spanning a several different technology stacks.
Everything you learn will go towards becoming an Architect. Architects could be thought of as uber-generalists. The broader the background, the better. There's not really any one source, be that a person or a job, for the experience that leads to a position as an Architect. If and when you finally do get a job as an Architect, you will likely have a mentor in that position to guide you in the specific requirements of that job.
If you want to become an Architect, focus on getting a lot of experience with many different types of systems. Email, Database, Web platform, networking, etc. Include multiple vendors and frameworks. Bust out of your comfort zone. My previous job dragged me kicking and screaming to Oracle, and I'm better for it.
Demand to be recognized for doing Architectural-level work in your current job. "Architect" means different things to different employers, so get your employer to give you their definition. If you can't get that from your employer (the definition or the recognition) then you may be limited in your current position. Ironically, I think having several positions over the last ten years helped me get my current job. Don't be afraid to move out to move up if that's your only option.