The legacy of the California Gold Rush turned San Francisco into the principal banking and finance center of the West Coast in the early twentieth century. Montgomery Street in the Financial District became known as the "Wall Street of the West", home to the Federal Reserve Bank of San Francisco, the Wells Fargo corporate headquarters, and the site of the now-defunct Pacific Coast Stock Exchange. Bank of America, a pioneer in making banking services accessible to the middle class, was founded in San Francisco and in the 1960s, built the landmark modern skyscraper at 555 California Street for its corporate headquarters. Many large financial institutions, multinational banks, and venture capital firms are based in or have regional headquarters in the city. With over 30 international financial institutions, six Fortune 500 companies, and a large support infrastructure of professional services—including law, public relations, architecture and design—San Francisco is designated as an Alpha(-) World City, and is ranked in 10th place among the top global financial centers.