It's an unmistakable Queen Anne creation in an area teeming with Federal and Colonial styles: the so-called Sunflower Castle at 130 Mount Vernon Street. And it's on the market now for $4,600,000. The 3,246-square-foot, 4-BR, 3.5-BA underwent, according to the listing, more than $2M in renovations, yet still retains the quirky sunniness, inside and out, that helped give the house its name. Its third floor had been the studio of watercolor artist Gertrude Beals Bourne, who lived in the house with her husband, architect Frank Bourne, and who rendered the space in a pre-World War I piece called the "The Artist's Studio—Sunflower Castle" (there are also sunflower carvings under the house's eaves, but the painting back-story's so much more quaint, no?). That studio, by and by, is now the master bedroom, with walk-in closet and spacious bath.