Being rich and famous has its downsides, what with the constant attention and being in the glare of the media spotlight, which means that you need to do some things on the down low.
One of those things is going to random parties at the Playboy Mansion, as it can make for a lot of unwanted headlines, in particular back in the day. A few celebrities who wanted to avoid that scrutiny decided that they would rather not be seen turning up at all hours at the gates of Hefner's famous house, so they built underground tunnels that lead straight to the mansion from their own homes.
According to Playboy.com, it seems that the discovery of these tunnels was made recently during the planning of a piece about Hugh's birthday, when they came across pictures of a huge excavation project on the grounds of the mansion, which it turned out was for the tunnels.
The staff found a number of polaroids of the excavation process, and after a bit of wrangling were able to get into the mansion itself to check out the blueprints, where they discovered plans for tunnels to the homes of "'Mr. J. Nicholson','Mr. W. Beatty', 'Mr. K. Douglas' and 'Mr. J. Caan'. We’ll go ahead and assume they’re talking about Jack Nicholson, Warren Beatty, Kirk Douglas and James Caan – all of whom lived near the Playboy Mansion during the late 1970s and early 1980s". Unfortunately, the tunnels were closed in 1989, so it seems that it's no longer an added feature for the properties in that area, but talk about a unique selling point.
You can go and check out the blueprints and pictures over on the Playboy site, where they also reached out to those named above for comment, but they have all decided to keep schtum on the matter.