Duane's take
Here's how the official marker tells it, and I'm passing it right along to you. Back in 1855, Polish settlers came to Bandera. That's the seed of this whole story.
Nearly two decades later, in 1874, those same settlers and their community built something meant to last: a convent and a Catholic school, raised from native limestone right there in the Hill Country. And that limestone, friend, is not a small detail. That stone has a stubbornness to it, a patience.
It would need both. Classes ran inside those thick walls until 1882, when everything except religion and music got moved over to a nearby frame school building. Think about what stayed behind in that limestone: religion and music.
Make of that what you will. The convent kept on, the Sisters living within its walls year after year. Then in 1922, somebody looked at that building and decided it needed more sky, so a second story was added right on top of the original limestone structure.
The Sisters lived there still, in that two-story native stone convent, until a new residence was finally erected in 1963. The parish school itself closed in 1968. That might've been the end of the story for a lot of buildings.
But in 1971, this one was restored. Today it stands as a museum. Polish settlers arrived in 1855, built in 1874, and that limestone is still there to prove it.
What the marker says
Polish settlers, who came to Bandera in 1855, built this convent and Catholic school in 1874. All classes, except religion and music, were moved in 1882 to a nearby frame school building. In 1922 a second story was added to the native limestone convent, in which the Sisters lived until a new residence was erected in 1963. The parish school was closed in 1968. Restored in 1971, this structure is now a museum. Recorded Texas Historic Landmark, 1975.