Warren Buffett? At his peak, Buffett's wealth is less than one-fifth this man's fortune. Bill Gates doesn't even come close. Neither does Wal-Mart (NYSE: WMT) founder Sam Walton or telecom magnate -- and current richest man in the world -- Carlos Slim. None of these men can hold a candle to the $336 billion fortune (adjusted for inflation) amassed by a name synonymous with wealth... John D. Rockefeller. But when I tell you I've found what I call my "Rockefeller" investment, I'm not saying it because I think it will make us billionaires -- even though I'd love to be able to say that. No, I call it my "Rockefeller" investment because of what this company invests in. This stock owns a rare breed of assets that are nearly impossible for small investors like you and me to purchase directly. Typically, only major companies or industrial titans like Rockefeller can buy them. Most people know Rockefeller became rich via his company, Standard Oil. And while I want to invest in the same sort of business he did, my "Rockefeller" pick has nothing to do with oil. But that's fine by me, because when you look closely at exactly WHY Rockefeller got rich, you realize Standard Oil didn't turn Rockefeller into a billionaire simply because it was in the oil business.No. Standard Oil made Rockefeller the richest man in history because the company held a monopoly in its market... while paying a fat dividend on the shares he held. And now, I've found an investment -- Brookfield Infrastructure (NYSE: BIP) -- that lets you own stakes in dozens of infrastructure monopolies across the entire world. And in addition to capital gains, it pays investors a 5.4% dividend each year to own it. In total, about 80% of the partnership's revenue is under contracts or is regulated.