Twenty years ago, Institutional Real Estate, Inc. held its first conference for institutional investors in infrastructure — also in Chicago. Key themes in 2006 focused on making the case for infrastructure investment, how infrastructure investment should be classified, how it should be benchmarked and how it fit into an investor’s portfolio. The past two decades have answered many of those questions, as the infrastructure asset class has proven its investment case several times over — with both notable successes and some high-profile challenges.