“I feel like I’m shutting down this part of South Congress that shouldn’t be lost,” Liz Lambert says wistfully in “Through the Plexi-Glass: The Last Days of the San Jose,” not knowing exactly how true she’d find that sentiment to be decades after she first said it in 1998 after she took a wrecking ball to the Hotel San Jose in Austin where the $30 a night rate attracted the kind of clientele who couldn’t afford longer-term housing solutions. It’s unrecognizable now as one of the city’s trendiest hotels, with a courtyard large enough to welcome Alabama Shakes to play during SXSW, and regularly brings in guests who make more in a year than the $550,000 Lambert initially paid for the place in 1997, but “The Last Days of the San Jose” captures the days when the run-down rooms were open to musicians who’d run late with payments, students at the nearby university that had fallen on hard times and those who were snakebit in one way or another from drugs to domestic abuse.

It speaks to the kind of pull Austin has that Lambert is every bit the misfit as the people she housed, albeit with a bigger bank account after working as an attorney and looking for a change of scenery like so many others, followed her gut to ask if the motel across the street from the Austin’s beloved concert hall The Continental Club might be for sale. The forethought to document her adventure getting her feet wet in the hospitality industry proves to be an extraordinary instinct when it preserves the memory of what South Congress was before the renovation of the Hotel San Jose led to what the street’s become today, clearing out those who gave the city its distinctive reputation in favor of those who chase authenticity with their checkbooks.

With footage largely from the first three years of Lambert’s tenure, the film shows in spite of the graffiti to scrub off walls and syringes to be cleared from behind bathroom mirrors, it was largely rewarding getting to know the folks that would check in to the Hotel, with a camera set up at the front desk to collect the most authentic view of Austin in the 1990s this side of “Slacker.” While it wasn’t uncommon for Lambert to see cops on the property without knowing at first why they were there, the anything goes spirit also yielded a place where a magical bagpipe serenade could happen without warning and fears that a fire might’ve broken out could easily turn out to be a BBQ with some pretty good looking chicken on the grill. The charm extends to Lambert’s desire to get to know some of her guests better, watching some find their footing and others struggling mightily, but all going about their lives in their own unique way.

Lambert occasionally sneaks into the frame, but largely exists as a voice behind the camera and as the film’s director (with Tina Gazzerro Clapp), she puts herself in the same uneasy position as she finds herself in as a businessperson, not obliged to feel any responsibility towards her guests beyond what’s been paid for, but ambivalent about whether that should be the case, particularly when she sees the costs of improving her business that don’t show up on a spreadsheet. It’s notable that Lambert had previously screened a version of “The Last Days of the San Jose” in 2005, at which point the effects of gentrification could already be seen in Austin, but perhaps less commonplace than it is around other parts of the country as it is now (hence the update) and as the hotelier expresses an uncertainly leaning towards regret, the film uses the remarkable perspective of the time that’s passed to show what leaves when the physical architecture that gives shape to communities disappears, with atonement coming for Lambert in admirably salvaging what she can in memory.

“Through the Plexi-Glass: The Last Days of the San Jose” will screen at SXSW on March 16th at 2 pm CST.