Oh, if the walls of the Gonzaga College High School theater could talk. . . .

Actually, that would freak people out since brick and mortar are not supposed to speak. But it would be interesting, too, for according to the folks at Gonzaga — the Catholic high school on North Capitol Street — theirs is the oldest continuously operating theater in the city. Who am I to argue with Jesuits?

The theater was completed in 1896 and presented its first play that February, a performance of “Guy Mannering,” based on the Sir Walter Scott novel. According to a writer from The Washington Post: “The hall was well filled with friends of the institution, who came predisposed to applaud.”

If that sounds a little catty, the next sentence was more positive: “Their applause was, however, in most instances well deserved.”

Every year since then, the Gonzaga theater has been home to plays and musicals, choral performances and oratory competitions. It hasn’t changed much in the past 116 years, which isn’t necessarily a good thing. The wings of the theater are nonexistent, as is the air-conditioning system (there is none). The hallowed boards themselves are scratched and warped. And this may be the last theater in Washington to have a fly system — the contraption to raise and lower scenery — that uses ropes and sandbags. It would be a good place to film a slapstick movie, with Keystone Kops getting konked on the head.

A $9 million renovation is underway to bring the 19th-century theater into the 21st century. Last week, I took a look.

“Theater is very important in Jesuit education, part of teaching the whole person,” said Paul Buckley, who graduated from Gonzaga in 1986 and returned in 1999 as a math teacher and theater sponsor. “It’s not just basketball. Jesuits are good actors, too.”

John “Doc” Warman was on stage with us. Doc graduated in 1957 and returned 10 years later to teach Latin and Greek. He’s the musical director for the shows, playing piano in the three-piece orchestra.

Both men trod the boards here as students.

“So many people say it was the centerpiece of their high school experience,” Doc said.

“There’s such a community that’s built up,” Paul said.

John Heard — the dad in the “Home Alone” movies — went to Gonzaga and acted in the plays. So did David Costabile from “The Wire” and Michael Bobbitt, who runs Adventure Theater.

They may have made the big time, but nothing sets an actor on his course like the crucible of the small time. If you’ve never been part of a high school musical, all I can say is, I’m sorry for you.

The last musical before the seven-month renovation started was “Annie Get Your Gun.” Annie was played by an actual female.

That hasn’t always been the case at the all-boys school. That first production of “Guy Mannering” featured a student named John Curran in the role of Meg Merrilies, the gypsy queen. For 70 years, boys played female roles. Directors tried to find shows that didn’t have women’s parts. “Mr. Roberts” was a favorite.

Eventually, the school got with the times and starting letting girls from area Catholic schools audition. The first co-ed production was in 1967: “Guys and Dolls.” (“Guys and Guys” just doesn’t have the same ring to it.)

Girls proved to be a great boon to the program. Where else could Gonzaga students be assured of spending several hours each day in close proximity with the opposite sex? A couple who met doing stage crew recently had a marriage. So, too, did a pair of cast members who were in “The Wizard of Oz” together. He was the Tin Man. She was Dorothy.

“Many prom dates are lined up in the course of the show,” Doc said.

The renovation will keep the theater’s handsome proscenium arch intact but will add a light and sound booth, a scene shop and rehearsal room. (They used to build the sets on stage, which made it hard for the actors to practice.) The fly system and HVAC will be modernized.

By long tradition, stage crew managers paint their names on the back wall. Today, it’s a colorful efflorescence with barely a bare patch. This bit of history will be preserved. I guess the walls do talk after all.

To read previous columns by John Kelly, go to washingtonpost.com/johnkelly.