Marzenna Niemoczynska started designing clothes in 1990 when she opened her first sewing studio, which was manufacturing clothes to the eastern market. In 2010 she established her own brand "303 Avenue" by setting a studio downtown in Warsaw. Marzenna opened her first flagship boutique in 2013 on Mokotowska Street, the heart of high fashion in Warsaw. The online store and second boutique in Poznan (based in Stary Browar, Art and Buisness Center) were launched two years later. 303 Avenue clothes are now regulary featured in Polish editions of magazines such as Elle, Harper Bazaar, InStyle, Glamour and others.