Nuveen Municipal High Income Opp Fund is a diversified, closed-end management investment company. The company's investment objectives is to provide current income exempt from regular federal income tax by investing primarily in a portfolio of municipal obligations issued by state and local government authorities or certain U.S. territories. It seeks to provide attractive monthly tax-free income, portfolio diversification and attractive after tax total returns. The fund invests in municipal securities that are exempt from federal income taxes. Revenue generated by the fund mostly comes from interest and dividend income, capital gain and other income.