There are two ways to design a group of subway stations.
You can make them all look alike, like soldiers in uniform, so that what they express is not their individuality but rather the wholeness and power of the transit system. The Metro in Washington, D.C., with its bold vaulted spaces in every station, is done that way.
Or you can make them all look different, like a hootenanny of hippies, so that what they express is the fact that they're all located in different places with different surroundings. That's the route Boston mostly takes.
One of the latest examples is the stunning new Aquarium station, designed for the Blue Line by Cambridge architect Harry Ellenzweig. Ellenzweig is the nearest thing we have in conservative Boston to a high-tech architect. He loves modern materials like steel, aluminum, glass, and even bare fluorescent tubes, and he loves the intricate detail, like that of an Erector set (if anyone remembers those), with which such materials must be fitted together.
You won't confuse Aquarium with any other Boston station. For one thing, it's a technical miracle. What you see is only a tiny part of what's been built. The depressed Central Artery, for example, passes across it overhead and is supported by its roof. That's at the top. At the bottom, slurry foundation walls have been extended 190 feet below the ground, just in case, someday, someone might wish to put them to use as the side walls of a rail tunnel between North and South stations.
The best of Aquarium, though, is the track level space itself. There was a station here before, and it's still here, now fully renovated. Ellenzweig's new section adds length to it, so the station can accept longer trains, and also width, so there's more room on the trackside platforms. Then he invents a sort of triple vaulted aluminum ceiling for his new section. It looks vaguely like a turtle shell with water wings. What's so impressive is that the middle arch of that triple vault is a seamless extension of the narrower vault of the old station. Old and new are reconciled here with real ingenuity. And just so travelers -- especially out-of-towners, coming from the airport -- will be able to tell this station from others, the walls are lined with bold ceramic tiles by artist Jun Kaneko.
Up at the sidewalk, the head-houses are crisply high-tech too, made mostly of metal and glass. One stands outside the Marriott Long Wharf hotel; another, across Atlantic Avenue, is next to the historic State Street Block. Ellenzweig plays a dangerous game here. He wants the head-houses to resemble one another, so you'll sense they're serving the same underground station, but he also wants them to respond to their immediate surroundings. So the State Street head-house incorporates a colonnade of granite, like the building behind it. And the Marriott's head-houses, of which there are two, are pierced by a brick wall like the hotel. Ellenzweig pulls off this strange game pretty well. Both the colonnade and the wall are inoffensive, but they do feel a little extraneous. They're a bow in the direction of conservative Boston's current belief that new buildings should always pick up superficial themes from context.
The Marriott head-houses are more fun to look at, with their angular shapes that seem to dive into the ground -- just as passengers are about to do, on the stairs and escalators inside. At State Street, the impressive element is the generous space of the mezzanine ticketing lobby, with its handsome red slate floor and gleaming glass and aluminum.
Unfortunately, because of the financial failure of the general contractor, the so-called ''punch list" of construction flaws hasn't yet been dealt with. But enough is here to make it clear that the Aquarium station is a credit not only to the architect but to the MBTA as well.
Robert Campbell can be reached at firstname.lastname@example.org.