Tommy Lee and Pamela Anderson's sons didn't just scoop up a 4-bedroom home, the place is more like a palatial estate!

The ranch-style property -- for which they paid $3,995,000 -- has a main house that's 3,700 square feet with 3 bedrooms, a fireplace in the living room, a modern kitchen adjacent to the dining room and a yoga retreat in the attic.

The home, tucked behind a wrought iron gate and towering oak trees, also includes a 400-sq.-ft. guest house and a massive swimming pool. There's even a bridge behind the gate with a paver-stone driveway leading to the motor court and 2-car garage.

TMZ broke the story ... Brandon and Dylan sold their crib in Malibu -- where they lived most of their lives -- getting their asking price of $3 million after 2 months on the market.

Now, 25-year-old Brandon and 24-year-old Dylan are all grown up, and putting down new roots.