Tonight in L.V.: St. Patrick’s Day Weekend, Flogging Molly, Das EFX, Calvin Harris, Flosstradamus, Ty Dolla $ign

When Irish eyes are smiling, tis like a morn in spring

With a lilt of Irish laughter, you can hear the angels sing

When Irish hearts are happy, all the world is bright and gay

When Irish eyes are smiling, sure they steal your heart away

It’s the day of Erin Go Bragh and Cead Mille Failte — allegiance to Ireland and 100,000 welcomes. The four-day St. Patrick’s Day Weekend starts today. There are four days of free music at Fremont Street Experience with 23 bands on three stages, among them The Hardwood Hotties, Luck of the Spandex, Finnegan’s Wake and Darby O’Gill and The Little People.

Zowie Bowie wears the green for his show there, and tonight through Sunday, our Welcome to Fabulous Las Vegas sign goes green. The High Roller at The Linq Promenade, The Cleveland Clinic Lou Ruvo Center for Brain Health and La Concha at The Neon Museum also goes green.

Zowie Bowie also joins Dennis Bono at South Point with Laura Shaffer, Gregg Austin and Second Wind From Motown Magic for Marty Allen’s early 95th birthday party.

The college basketball bash of the year is The NCAA Tournament, and it’s celebrated like no other place on Earth than here. Last year our sports books took $300 million in wagers with a profit hold of $15 million. Experts are predicting even more before the end April 3 in Arizona.

NBA legends Larry Johnson, Moses Scurry and Anderson Hunt host the block-long Downtown Summerlin tipoff tailgate to kick off March Madness. Check your skills against theirs.

There are no less than 25 venues to party, gamble, eat and drink during March Madness. The gorgeous girls from Rehab at The Hard Rock host events, and retired NBA player Thurl Bailey (Utah Jazz, Minnesota Timberwolves) is at Westgate with Bud Light Girls for Hoops Central.

The free college hoops viewing party starts at Westgate with Celebrity Bracket Challenge. Sports, music and entertainment stars have submitted their brackets to win $5,000 for charity. Celebrities participating alongside Thurl: Nate Morris for Boyz II Men House; Joey Fatone for Fatone Family Foundation/Autism; Terry Fator for The Arthritis Foundation; Valentin Chmerkovskiy for Pencils of Promise; and Maksim Chmerkovskiy for Alfalit.

Also: Tony Dovolani for Cancer Research Institute; George Wallace for Clark County Foster Care; Louie Anderson for Metro Deaf School; Rick Harrison for Epilepsy Foundation; Corey Harrison for Autism Speaks; Richard Harrison for Safe Nest; Gordie Brown for Cure 4 the Kids; Vinny Guadagnino for The Humane Society; Pia Zadora for Project Focus; and Jennifer Romas for Shade Tree.

Hoops and Hops is celebrated at The Cosmopolitan of Las Vegas sports book; Tropic Beauty swimsuit sirens are at Light at Mandalay Bay for two nights; Borracha is your best bet at Green Valley Ranch; Hearthstone has heart at Red Rock Resort, Clique at The Cosmopolitan and The Still at The Mirage are winners; and Topgolf behind MGM Grand tees off.

Carson Kitchen chef John Courtney will serve a corned beef and cabbage sandwich with Guinness mustard for $15. Additionally, guests can enjoy a boilermaker of Irish Whiskey for $5 with purchase of any beer at regular price. These specials are valid on March 17 only.

Florian “Venom” Kohler, who nailed six new Guinness World Records on Monday, gives an exhibition at Gorilla Cafe on East Tropicana.

Flogging Molly headlines Boulevard Pool at The Cosmopolitan.

Jason Isbell rings loud and clear at House of Blues at Mandalay Bay.

Our Tao Group at The Venetian moves west to L.A. for the grand opening of restaurants Tao, Beauty & Essex and Luchini and Avenue nightclub at the new hotel Dream in Hollywood.

Das EFX is at Throwback Thursdays at LAX at The Luxor.

Calvin Harris spins at Hakkasan at MGM Grand.

Benny Black is behind the wheels of steel at Ghostbar at The Palms.

Flosstradamus peers into the future at Intrigue at Wynn Las Vegas.

And Ty Dolla $ign makes money behind the 1’s and 2’s at Tao at The Venetian.

TOMORROW’S TEASES

ABC’s Season 21 “The Bachelor” star Corinne Olympios host St. Patrick’s Day at Hyde Bellagio, and my pal Irish barkeep John O’Donnell hosts his party at Crush at MGM Grand. All seven bars at Grand Bazaar Shops at Bally’s are part of a bar crawl for green beer and Jameson Whiskey shots from 10 a.m. Friday to 4 a.m. Saturday.

We’ll have our weekend celebrity preview Celebrities in L.V. with Dana Carvey, Jon Lovitz, One Republic, Gavin DeGraw, Andy Grammer, Flavor Flav, Scott Disick, Pitbull and more.

And here and in Friday Neon of The RJ, our Q+A with Mrs. Nevada-America winner Stephanie Barrett and 1 OAK at The Mirage Managing Partner Eli Pacino and a review of the new Oyster Bar at The Hard Rock Hotel.