Realty Income (O -1.16%) has been a magnificent investment over the years. The real estate investment trust (REIT) has delivered consistent returns and dividends. It also has a strong balance sheet, putting it in an excellent position to continue growing. These features should make it a core holding in any investment portfolio. Here's a closer look at everything the REIT has to offer.A proven performerRealty Income has been a model of consistency over the years. The REIT has delivered a positive total opera ...