Well, frankly, I think with the bitcoin's market value now it's not possible anywhere in the world now to build or buy a mansion with 0.1 btc. But we'll see it in the future if bitcoin will actually reach like $200k USD or more then maybe you can build or own a mansion.
Aside from that option, there's some mansions that are old enough historically, maybe that 0.1 btc of yours can afford it depending on the place or current owner.