An air carrier Captain reported lining up with the wrong airport on approach to OKC; even though he had the localizer tuned properly. Neither pilot was very familiar with OKC area.

Narrative

After being cleared for the visual approach into OKC; we started a descent only to realize that it was not to the correct airport. As we realized our error; the Approach Controller advised us to climb and proceed on a different heading. We complied; and inquired if we had caused any problems. Controller replied; 'No worries.' After landing I phoned OKC Approach to make sure that all was well. I was told that there was no problem; it is a common mistake. We were running the localizer for 17L; which helped to alert us to the problem. The runways are aligned in a similar fashion at both airports. I had only been to OKC once before; in the dark; so was unfamiliar with the surroundings; although I did notice a lake that I hadn't before. My First Officer had been to OKC a few times; but was flying in the right seat of a new airplane; and was initially concerned with flying the airplane. He had his doubts about the same time I did. So; what did we learn? Even with back up (the localizer); it is important to keep your head up and pay attention to all visual cues; and to remain vigilant at all times.