The Playboy mansion and its supporting structures -- an aviary, an enclosure filled with dozens of frolicking monkeys, a bunny hutch (for the four-legged kind, lots of them), a zoo-quality aquarium, a game room with guest rooms, and that famous grotto with adjacent changing rooms -- sits on about five lofty, fastidiously maintained, tranquil acres just off Santa Monica Boulevard in Holmby Hills.

Peacocks and African cranes roam the back lawn, resting in tall trees that shelter the rabbits and lead to the aviary. A black Doberman (Leilynd) and a yellow Labrador (Dior) roam there, too, usually with their old friend Hugh Hefner, 61, and recently with Hefner's new friend, Kimberley Conrad, 25.

Now, with the scene set, let me tell you that I did not approach the Playboy mansion for the first time in my life last evening with such cool powers of observation. My mind raced with the speed of a hare being chased by a hound as I pulled up the driveway lined with Rolls-Royces and Maseratis. And, quite honestly, the smile on my face was the one boys form when they first realize that girls are different in a nice way.

Most men remember that moment and, at least for a while, probably link it to Playboy and Hugh Hefner, too. We assume everything we surreptitiously thought about, he did without guilt.

To enter the great stone mansion for the first time, therefore, becomes a rite of passage in reverse (at least it certainly was for me), and I report to you here the good, the bad, and the shocking goings-on at that fantasy world.

The Good

There are an awful lot of ways to entertain yourself at Hef's (his favorite name) without getting in trouble, and a health consciousness is becoming important to the Playboy life style.

A few years ago, I am told, the spiraling staircase in the pool house led to all types of rambunctious party space. It now leads to an aerobic dance floor, stationary bicycles, and a Nautilus work station. Several ladies were working out during my first visit, and I tried to be helpful with a coaching tip or two.

Kim Conrad (Miss January) worked out with me and Conch Out coordinator Eric Jensen on our second visit. Conrad has bounced with energy since childhood. "I was always playing basketball and roller-skating and moving," she says. She now walks fast, dances and lifts weights ("only for toning") at least three days a week. There's not an extra ounce of fat on her.

Very few of the people who hang around the game room -- a separate four-room building loaded with video games and old-fashioned pinball machines -- have any extra fat, either. One very sleek woman with long, blond hair told me she stayed trim by jogging up and down the neighboring streets, and stayed peaceful by honing her skills at Donkey Kong. She has yet to beat the reigning champ at that game, Johnny Carson.

If the games don't keep you wholesomely entertained, I recommend either the Cinemascope-sized tennis complex, a tour of the mansion's animal kingdom (Hefner has a private zoo license and four full-time zoo keepers), or a visit to the media room (two people on staff simply monitor television broadcasts around the world 24 hours a day). You don't have time to get in trouble here because there are a lot more fascinating things to do.

The Bad

I do have two complaints. The first concerns temptation. At every turn, there were plates of snacks, and none of them looked like healthful food to me. Right by every machine in the game room sat either a bowl of M&M's or a plate of sugar cookies. On the sideboard in the main dining room -- right by the table where I sat and chatted with Jessica Hahn for 15 minutes without recognizing her -- were piles of Rice Krispies treats and very salty nuts. I found myself yearning for a carrot.

And then there were the robes in the eight or nine changing rooms spread around the grounds. The robes were very nice and plush, but they all seemed one size: short. One could catch his or her death of cold or embarrassment walking from the pool room to the swimming pool and grotto.

The Shocking

First is the danger of swimming in the pool and grotto with George Plimpton. The grotto sits in the middle of the free-form pool covered by a small, hollow volcano. Two waterfalls pour off the volcano. Two free-form Jacuzzis and a large swimming area fill the volcano. As George and I first swam in the grotto, he pointed to the far wall and said "Under there, Remar ... you can swim under there and go out to the pool!"

Without hesitating, I held my breath and shot down into the water. BAM!

I floated groggily to the surface. "Oh, Remar," Plimpton said, "I think the tunnel's over there." He pointed in the opposite direction.

The Final Shocker

The greatest shock of my coming-of-age in reverse has to do with Hugh Hefner himself. This is his kingdom, and not a cue here comes from anyone else. And though this kingdom may be based on a liberal and material attitude about life, it is not filled with licentiousness. Giggles don't echo down every corridor, and splashes from the pool seem to be coming more these days from lap swimming than frolicking.

Even the changing rooms themselves seemed pretty wholesome to me. Sure, the robes were short. But in every medicine cabinet was a fresh bottle of Pepto-Bismol -- no doubt to counter the effect of all those sugar cookies and M&M's. Somehow that seems more like home than fantasyland, I'm glad to say.