Carnuntum

The answer for anyone tired of imagining walls from knee-high foundations. On the Danube between Vienna and Bratislava, Carnuntum has rebuilt a Roman town quarter on its excavated foundations, using archaeological evidence and ancient building techniques down to roof tiles fired in a reconstructed Roman kiln, so you can walk into furnished rooms in houses such as the House of Lucius and the House of the Oil Merchant. The reconstructions show the town as it was in the late third and early fourth centuries AD. Purists may balk, but as a way to grasp room sizes, heating and daily clutter, nothing else on this list does it as well. An easy day trip from Vienna.