I wouldn't try to pursue architectural photography right off the bat. Instead, see if you can shoot a realtor friend's listings (do one or two for free/very cheap to get a hang of it and see if you like it) and try to get in that way. It's all who you know. After a couple of years shooting real estate (using lights), try to shoot for some interior designers or stagers who are friends of the realtors that you've been shooting for (trusting that your work is getting better and better).
The reason you'll want to use lights is because the natural progression is RE > ID > Arch work. And trust me nobody is shooting professional, magazine-quality interior design work via HDR. So shoot for some interior design clients, nail the shots, make the spaces look great, get a few shots in some magazines, and so on.
After some more time spent doing that, you will have interior design clients who know architects and can refer you. Do be aware, however, that architectural photography is REALLY tough right now - architects' budgets are the tightest that they have been since the dawn of time, and the expectation of perfection is absolutely off the charts. I have found that in many cases, the tight budgets coupled with the crazy high perfection standards is often not worth it, as it leads to me doing way more work and 'perfection-izing' if you will, but I do have some awesome clients that I really like working with and who constantly keep me stimulated with interesting structures. That's how I see it anyway, it's nothing against architects, but I have found that I can be more creative and relaxed while shooting interior design, and often bag more money for the same amount of work than I would shooting architecture.
That being said, if you put in the time there is no reason you can't be a successful architectural photographer, just be aware that the market conditions are kind of iffy right now and you need contacts and referrals to get anywhere. It's definitely one of, if not the hardest, fields to get into as a full time gig.
Of course you can jump around and not do everything in 100% that order, but that's generally how it works. Architects and designers I find are very loyal to their clients and will refer you around if they like your work. Also don't forget hotels, restaurants, and most any business with a storefront location will need great photography and those are good options to check out as well.
It is a long process no matter how you slice it, though.