In the 1970s, world-renowned architect Richard Meier and a younger colleague, Michael Harris Spector, were both interviewed as finalists to design a home on a five-acre property in Old Westbury. Meier ultimately won the competition, adding the striking “White Castle” to his modern portfolio. But Spector, founding principal of the Spector Group, who would go on to collaborate with Meier on the federal courthouse in Central Islip, did end up having a say in the end: He later purchased the Meier-designed home on Bacon Road and added his own touches, renovating the kitchen and bathrooms, replacing the acrylic windows with nonbreakable glass, and turning four of the bedrooms on the third floor into a gym and a study. During the summer, Spector put the home on the market for $11.8 million, listed with Lois Kirschenbaum and Debra Quinn Petkanas of Daniel Gale Sotheby’s International Realty.