Boston is changing — so much so that a 600-foot tower near the edge of Boston Harbor is no longer unimaginable.

With a final blessing from Matthew Beaton, the state’s top environmental regulator, Don Chiofaro’s dream of building a 900,000 square-foot fortress in the clouds on the postage stamp of Boston’s waterfront is another step closer to reality. On April 30, Beaton gave initial approval to a zoning plan that allows it. He has until June 11 to affirm his decision — or do what he should do, and reconsider it.

A green light would be another sign that quaint old Boston worries about shadows and scale are increasingly obsolete — just like other New England peculiarities, such as referring to soda as “tonic.’’ It also makes a mockery of Chapter 91, the state law that is supposed to govern access and development along the waterfront. As Beaton notes in his report, zoning regulations limit height at the site of the Chiofaro project to 155 feet. To allow additional building height, “I must find that the proposed size be relative and modest,’’ he wrote. And in what is clearly an insult to that mission — he did.

The battle over the Harbor Garage project has gone on for a decade. The late Mayor Tom Menino didn’t want it, and nearby residents still don’t. But the relentless Chiofaro found a bigger-is-better development soul mate in Mayor Marty Walsh and in Charlie Baker, a governor willing to go along with their wishes. Also key to moving the project forward was Chiofaro’s agreement with the nearby New England Aquarium to create a fund worth up to $30 million to recoup revenue lost during construction. He will also contribute $10 million to a proposed “Blue Way’’ park the Aquarium plans to build on Central Wharf; and $300,000 to accommodate a new waterfront park near the Chart House on Long Wharf.

Beaton found those offsets “will serve to mitigate and compensate for the adverse effect of the significant height and the maximum net new shadow associated with the proposed height substitution for the harbor garage site.’’ It probably didn’t hurt that former governor Bill Weld represented the aquarium and helped broker the deal.

The Conservation Law Foundation, Harbor Towers, and InterContinental Condominium — longtime opponents of the Chiofaro project — have filed a request for reconsideration with the state. The Conservation Law Foundation is also threatening a lawsuit if the Chiofaro tower, and a 305-foot tower on the Hook Lobster site, get a final OK. Even with that, the developer must still present specific building plans to the City of Boston.

Resistance to this plan is usually cast as the selfish desire of abutters to protect views and parking. Yet if this building goes up and a wall of buildings follows, the loss is greater than any one sightline. Billions were spent to take down that barrier to the waterfront known as the Central Artery. Do we really want to trade an old elevated highway packed with commuters for a row of shiny glass towers packed with rich people?

Not if you look at Walsh’s “Imagine Boston 2030’’ website. When asked to envision the waterfront of the future, people imagined ferries, a canal, easy access from all neighborhoods, enhanced public spaces, and a more connected Harborwalk. If anyone wanted a 600-foot tall building, it’s not listed on what is supposed to be the official blueprint for the city’s planning priorities.

Of course, cities change. Boston’s waterfront, once a place no one but rats wanted to be, is now highly coveted real estate. The city itself is increasingly cosmopolitan and global. But Boston should not give up everything that makes it special just to prove it is no longer parochial. A 600- foot tower will be almost half the size of the Empire State Building, which is 1,250 feet high (1,454 feet to its tip) and nowhere near the New York City waterfront.

Imagine that.

Joan Vennochi can be reached at vennochi@globe.com. Follow her on Twitter @Joan_Vennochi.