Microsoft Corp. (NASDAQ: MSFT) co-founder, former CEO, recent “Chief Software Architect,” and world’s richest person for 13 years Bill Gates is not known for his investing so much as his business leadership – he didn’t invest in Microsoft, he built it. Nonetheless, Bill Gates is a pretty savvy guy, and he presumably has very savvy guys managing his investments (with a best friend like Warren Buffett, one would hope at least).

Obviously Gates’ wealth comes from Microsoft, but he has made a significant effort over the years to diversify his holdings through his private fund Cascade Investment LLC. In a recent The Motley Fool piece, some of Cascade’s holdings were examined:

•    Berkshire Hathaway (NYSE: BRK.A)
•    Canadian National Railway (NYSE: CNI)
•    Otter Trail (NASDAQ: OTTR)
•    Republic Services (NYSE: RSG)
•    Six Flags (NYSE: SIX)

Berkshire Hathaway is not surprising, given Gates’ relationship with Buffett, and the good sense for anyone, regardless of whether you personally know the Oracle, of investing in the company.

Cascade also seems to have a penchant for unglamorous businesses like railroads, Canadian National Railway, and trash disposal, Republic Services – both of which have done well for Cascade over the last 12 months, returning 7% and 13% respectively.

To investigate Cascade yourself, look for its 13-F filing with the SEC.