Chestnut Square Historic Park gathers several old McKinney buildings into a walkable village just south of the downtown square. Houses, a chapel, and period rooms give the city a more concrete past than the polished storefronts alone can provide.
It is best when tours or events are running, but even a quiet visit helps anchor McKinney's historic-district feel. Combine it with the courthouse square, lunch downtown, and a slow look at the side streets if you want a compact introduction to the city.