Dwight Howard -- Unloads Insane Orlando Mansion ... for $3 MILLION Loss

Dwight Howard is finally cutting ties with the city of Orlando -- selling the amazing mega-mansion he abandoned there over two years ago ... for a HUGE loss, TMZ Sports has learned.

Dwight -- who was drafted by the Magic back in '04 -- originally dropped $7.78 mil on the 11,025 sq ft Longwood, FL property when it was built in '08 ... but now the place could be yours for a cool $4.9 mil.

The house is incredible ... built in the Gothic style and nicknamed the "Chateau D'Usse" -- after the famous French castle -- it has 5 bedrooms and comes complete with vaulted ceilings and fancy designer furniture.

It gets better, according to our friends at at Reatlor.com, you'll also find a massive kitchen with separate food prep area ... a large family room with two-side fireplace leading to a man cave (complete with pool table and wet bar) ... a temperature controlled wine cellar ... and a tiered movie theater.

But the outside is where things get really awesome ... there's a covered patio with fireplace and entertainment center ... an incredible pool with water-falls, water slides, a swim-in grotto ... and (best of all) a LAZY RIVER.