In 2010, Castellano co-created the Hester Street Fair (HSF), an outdoor community. HSF is a hybrid incubator and launching pad for small, independent businesses and artists specializing in unique handmade goods and artisanal food.

HSF supports a community of artists, collectors and first-time entrepreneurs, while giving shoppers the joy of discovering the next “big thing.” To date, 15 of the businesses that started at the HSF have gone on to open brick-and-mortar storefronts. 

Every weekend, hundreds of vendors rotate over 60 spaces, creating one of the most dynamic outdoor events in New York City. In addition to the weekly fair, the Hester Street team has also produced Hester Nights at the Eventi Hotel, Hester Hollywood, the annual Grub Street food festival, holiday pop-up markets, the snack bar at HBO Bryant Park Summer Film Festival, and the cafe at the New Museum.