 Manhattan contained approximately 520 million square feet (48.1 million m2) of office space in 2013, making it the largest office market in the United States, while Midtown Manhattan is the largest central business district in the nation.Silicon Alley, centered in New York City, has evolved into a metonym for the sphere encompassing the New York City metropolitan region's high technology and entrepreneurship ecosystem; in 2015, Silicon Alley generated over $7.3 billion in venture capital investment.High tech industries including digital media, biotechnology, software development, game design, and other fields in information technology are growing, bolstered by New York City's position at the terminus of several transatlantic fiber optic trunk lines, its intellectual capital, as well as its growing outdoor wireless connectivity.