In a frantic end to the Q3 shootout, Alonso, Alpine's Esteban Ocon and Ferrari driver Charles Leclerc all traded provisional pole until Red Bull world champion Max Verstappen clinched his first Monaco pole with a hair-raising final sector.
The Dutchman said he "clipped a few barriers" in the process and Alonso also admitted he took a few "uncomfortable risks" in his hunt for his first pole since 2012's German Grand Prix, almost 11 years ago.
With overtaking nearly impossible on the narrow streets, there is annual discussion on whether Monaco deserves to stay on the calendar or whether modern F1 cars have outgrown the principality.
There are also recurring complaints about Monaco's lack of suitable infrastructure and logistical challenges, a result of the paddock being crammed into the tight constraints of its harbour with no clear scope for expansion.
The prospect of a dull Sunday parade remains but, according to Alonso, Saturday's unique qualifying magic shows Monaco - which was part of the the first world championship in 1950 and has been a permanent fixture since 1955 - still has its place in the modern era.
"I think the lap is high adrenaline and if we see also how it looks on TV, when I was sitting in the car, you see the whole Monaco today on a sunny day, I think is a very unique place," said Alonso.
"Even last year, when there were talks that maybe Monaco was not on the calendar for the future, it doesn't sound right. It has to be, always."
Polesitter Verstappen said a qualifying lap around Monaco's twisty and unforgiving two-mile layout gets his heart pumping like no other session.
His excitement was audible on the team radio when he breathlessly blurted out to his engineer how close he had been to crashing on his magnificent pole lap, a fate which befell team-mate Sergio Perez in Q1.
"I can feel that every time you jump in the car, your heart rate probably is a bit higher than on other tracks when you do a qualifying lap," Verstappen explained.
"Because you know that when you make one tiny misjudgement or whatever, you end up in the wall.
"From all the street circuits we do, this one over a qualifying lap is definitely the hardest to nail and you feel it when you jump out of the car. You're full of adrenaline and your heart rate is still higher than other qualifyings."
Monaco local Leclerc, who took pole in 2021 and 2022, felt that Saturday's qualifying spectacle makes up for Sunday's lack of entertainment.
"Race day, yes, it is not the most exciting race in terms of overtaking but the Saturday is just incredible," he added.
"The feeling that we have over a qualifying lap is so good. It's like nowhere else on the calendar."
