When Barry Katz first saw the property on Lower Westheimer that was to become his restaurant, it was so unfinished all he remembers is the muck.

"It was literally mud," he said.

But from that muddy patch he built a restaurant that Houston has come to embrace as its favorite around-the-clock eatery serving a gargantuan menu of classic sandwiches, burgers, dinner entrees, breakfast plates and desserts.

In that way, Katz's deli hasn't changed a bit since it opened at 616 Westheimer in 1998. Well, at least not until Katz decided to give the restaurant a major face lift for its 20th anniversary. This week the restaurant is celebrating that top-to-bottom renovation with a party May 3 at 8 p.m. to benefit The Women's Home, its neighbor at 607 Westheimer.

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In addition to upgrading nearly every item on the menu in some fashion, Katz's also has a new bar menu and an improved cocktail program. But the 46-year-old restaurateur is most proud of the redesign lavished on the 6,800-square-foot restaurant courtesy of Austin-based architect Michael Hsu. A friend of Katz's, Hsu brightened the space with fresh New York iconography: subway tile, subway map symbols and typography and framed photographs of iconic Big Apple imagery. Every inch of the restaurant has been buffed and sports new lighting and light fixtures, tables, chairs, booths and artwork. Even the music is new.

And somehow the 2-month-long project was completed while never once shutting down, making good on the restaurant's motto: "Katz's Never Kloses."

"It was really hard on the staff and our guests," Katz said. "We went to lengths to keep our mantra of never closing. It was like changing a flat tire while the car was still moving."

But Katz did it, which wouldn't surprise his deli forebears not a bit. His father Marc's family emigrated to New York in the 1950s where they eventually ran restaurants, a candy store and butcher shop. His mother Tillie's family moved to Houston from Poland in 1951 as Holocaust survivors. Katz's parents moved to Austin in 1976 and that's where Katz's delicatessen was born, opening in the knish- and pastrami-deprived capital city in 1979. That deli had a long, colorful run before closing in 2009.

The Austin Katz's is where Barry Katz got his training in the restaurant business since he started working there at age 12. He was a dishwasher working every summer and after school. He worked his way up to a server, then a manager, then chef and eventually business owner. Along the way he earned a degree from the Culinary Institute of America and a degree in hotel and restaurant management from Florida International University.

"You have to love this business," Katz said. "I knew from a young age I wanted to be around this."

Katz opened his own restaurant in Houston in 1998 on a part of Westheimer that has become a hot culinary stretch in recent years. His two-story deli seems perfectly at home against the new coffee shops, upscale Japanese, Tex-Mex, Italian and French culinary neighbors. And entirely comfortable slinging Reuben sandwiches, hot open-face roast beef sandwiches, chopped chicken liver, stuffed cabbage rolls, meatloaf and gravy, challah French toast, cheesecake and bagels and lox at all hours of the day.

A new weekday happy hour from 3 to 7 p.m. is a chance for Katz's to draw a new crowd for $6 cocktails and $5 glasses of wine to accompany a new happy hour bar menu of mini sliders, mini Reuben sandwiches, fried pickles with ranch dressing, macaroni and cheese balls, and hummus and whipped feta dip with bagel chips (all $5).

Katz's recognition of growing an audience is part of what motivated him to upgrade his restaurant. New York-style American delicatessens are a dying breed he said and will continue to fall "because they're not reinventing themselves."

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The new Katz's, he said, represents the evolution of his grandparents' deli business. "It's blending the old and the new," he said. "It's the next chapter of the deli business."

And after 20 years in business, Katz said he continues to find daily joys in operating a deli. In fact, it doesn't seem like two decades, he said. "It feels like two years. It doesn't feel like work," he said. "I love this city and people and that inspires me to start a new chapter."

Kat's Deli, 616 Westheimer, 713-521-3838; ilovekatzs.com. For 24 hours beginning with the party May 3, Katz's will donate 20 percent of all sales to The Women's Home.