As you enter Trinity’s downstairs Dowling Theatre, you find yourself face to face with a huge brick building, giving the illusion of looking into the windows of a fifth floor NYC apartment building.

Are we going to have to watch Neil Simon’s “Barefoot in the Park” through the windows?

The lights dim as the walls slide back and we are nearly inside the barebones flat, looking up at a broken window in the skylight and doors leading to a bathroom without a tub and a bedroom that is too small for a double bed.

Enter Corie (Rebecca Gibel), a perky newlywed who is excited and proud to have found a home for her and her new husband, Paul (Charlie Thurston), an uptight lawyer about to try his first case.

Corie is in a state of bliss. Never mind that there is no heat, no furniture and a six-floor climb (five floors plus a big “stoop”).

Paul arrives, exhausted from his day at work and eager to try his first case the following morning. Corie has romantic notions about their first night in the new apartment, while Paul needs to prep for his case, with nowhere to find peace and quiet or even sit down.

That’s the setup for Simon’s dated comedy (It is the early ’60s), which is filled with the playwright’s sometimes funny, sometimes corny humor.

I have seen Simon’s plays many times over the years, usually in amateur and college productions, and I must admit that I have never been a big fan. But then, I have never seen what the talented Trinity troupe can do to a dated, lengthy Simon play, with some sharp direction by Michael Perlman.

Gibel and Thurston, a young couple in real life, bring freshness and believability to their relationship. You’ll be pulling for them right from the start, as Paul tries to cope with his wife’s impulsive choices, right to the breaking point, where instant incompatibility leads to talk of divorce.

This is romantic comedy at its most romantic, so you just know that there will be a happy ending. And what an ending Trinity has in store for you. I won’t give it away, but remember the set and the ledge on the fifth floor.

The subplot involves Corie’s mother (a hilarious Phyllis Kay) and a neighbor (an equally hilarious Stephen Berenson) manipulated into a blind date by Corie, much to the displeasure of Paul. Two brief appearances by Uche Eleueza, a third-year Brown/Trinity MFA student, as a telephone repairman, add to the fun.

And who is this George Spelvin who appears for a brief moment as a delivery guy? It’s a theatrical inside joke that Stephen Berenson told me can be clarified by going on George Spelvin’s own page on Wikipedia.

All of this makes for some outrageous physical comedy choreographed and performed to perfection. Just watching the characters come through the door after climbing six flights (remember the front stoop) is enough, but Thurston’s rubbery body makes for some Olympic-type moves that had the audience laughing hysterically…and at one point joining in a group fearful cry.

You can read all kinds of things into “Barefoot in the Park,” but I prefer to just take it as presented. “Don’t go to bed angry” is about as deep as I want to get. Gender identification, the role of women in a marriage, incompatibility and opposites attracting are all figured into a play that need not be overanalyzed.

Take it for what it is: Trinity taking a Neil Simon play and making it a fun evening of theatre that will leave you chuckling all the way home.

“Barefoot in the Park” is at Trinity Rep through Dec. 21. Call 351-4242. It will put you in the right mood for the holiday season.