it is about 24 feet by 48 feet but the concrete walls are over one foot 6 so the knot spaces about 20 and a half by 46 and a half feet.the raised exercise platform where the photo is taken is about 16 feet, and it is raised up by about 6 feet and the mechanical equipment is underneath. The space is heated and cooled by a geothermal heat pump unit and there is also a lot of dehumidification.

Wow, thanks for all the information, now to translate it to metric, :). After posting my question I looked at the rest of this house and absolutely love it! You should add the designation 'storybook' to its description as that is what it is, and what I am wanting to build myself. 'Storybook' accounts for the eclectic nature of the build and includes the 'old' sections and the 'fantasy' elements. Brilliant house!

Hmm. Metric.... that would be about 8m x 16m or a little less than that. Wider would have been better as the 3 point line of the court is not wide enough. Thanks for the tip on making it a storybook!