Well, synagogues can be designated and decorated as such, or can really be any room which is used for prayer. If you design a synagogue from scratch and deal with all the possibilities in decor, you also have to have an ark at the front to hold the torah scrolls, an eternal flame (lightbulb) in the front center, a readers table for torah reading, and a prayer lectern for the one who leads the services.
Pews vs. Seats, the physical divider between men and women, balconies and lots of other stuff comes in to play. When we pray, we try to (in America, at least) face towards Jerusalem which is in the East, so the ark should be in the front when we face east, but architectuire makes this not always the case.
There won't be any statues and while there may be artwork (stained glass?) odds are it will not show anyone in particular, but will highlight words or vague shapes.