We've just completed a contract in Germany with a 25 place underground garage (block of apartments), biggest issue will be found conditions and location.
I'd you have good ground conditions and no adjacent buildings to support, it will just be expensive, but otherwise it wil be very expensive (but fun)
My house would also suit a ramp down in the garage and a big garage under the rear garden. I'd do a pool at the same ime in the garden.
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