Big Modern Gym for Sims 3
This gym is SO much better than the ones that are available in Sims 3.
Included in the download is a pool, picnic area, training area, huge bathhouse/bathroom, a basement AND an underground pool.
According to the creator, no custom content was used so you don’t have to worry about strange things happening in your game.
The furnished lot costs 109,423§ and the unfurnished lot costs 89,775§. Considering that this is a 30×30 lot, I think that both of those prices are really reasonable.
This is going to sound completely weird, but my favorite parts are the bathrooms.