Travis is the newest resident in Brentwood -- one of L.A.'s ritzier neighborhoods -- after dropping $23.5 million on the epic, 16,700-square-foot mansion ... which could double as the Getty Center museum, if needed.

Seriously, this pad is almost out of this world, with 7 bedrooms, 11 baths, 3 full floors of ultra-modern living space ... and it sits atop a hill with panoramic views over the city.

And, get this ... he got it for a bargain! The mansion was first offered last summer at nearly double the price -- $42 mil -- before undergoing 2 big price chops. That's when Scott swooped in and covered the entire purchase price in cash ... which is still one of the biggest in L.A.'s luxury real estate market.

Along with what you see, the property also boasts a 20-car "auto gallery" of a garage. Other highlights include a gym, bar, sauna, 15-seat theater, wine closet, massive pool and a lot more. Check out the gallery and you'll see ... this house is more like a resort.

Trav's new home's not far from LeBron James' either.

Of course, the rapper still has a $13.5 million mansion in L.A. -- which he co-owns with Kylie Jenner -- so that might be on the market soon. Or, who knows ... maybe he'll keep both.

Seems like he can afford it.