You’re already carrying a pass to one of the coolest real-estate tours in the city: It’s your MetroCard.

The city’s subway stations are a mishmash of designs across the decades, everything from early 20th century ceramics to splashy 1970s colors schemes. And the evolution continues with ambitious station construction now underfoot — and a possible redesign of the iconic subway bench on the way.

“The typical New Yorker response to the subway is ‘get me in and out as fast as possible,” said Anthony W. Robins, author of the book “Subway Style” and an architecture expert. “It’s worth it to stop and look around. There’s wonderful stuff.”

City Beautiful
The masterminds behind the original subway, which opened in 1904, wanted it to be a “very pleasing feature to the traveling public,” according to an early report. Designers believed that even the lowly subway should be a work of art, in keeping with the era’s “City Beautiful” movement. Cast-iron ceramics plaques and specialty tile still adorn many stations along the numbered lines in Manhattan, including Astor Place (the famed beaver plaques) and Bleecker Street on the No. 6. The quality of the terra-cotta, mosaic and bronze was so fine, that the transit company eventually had to substitute cheaper materials or risk going bust, Robins said.

Moderne
In the 1930s, underground lines such as the E and F in Queens were built with a modernist eye. Mezzanines were bigger and airier, and strips of colored tile traced plain, white walls. The distinct hues were supposed to identify individual stations, although the complicated scheme never caught on with straphangers, Robins said.

The color strips got funkier in 1950, when they were placed in undulating curves along the 179th Street station on the F line.

High modernism
The city was looking to inject some heartening life into the decrepit system during the 1970s. Famed architect Philip Johnson was tapped to make over the 49th Street station on the R line with bright red bricks and terrazo floor tiles. The walls of the Bowling Green station were also bathed in orange, but the full Johnson treatment never rolled out across the system.

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“We always wondered what the architects were thinking when they put in the orange,” said Judith Kunoff, NYC Transit’s chief architect.

1980s experiments
As the system continue to decline, officials added some style to new Lexington Avenue/63rd Street, Roosevelt Island and 21St-Queensbridge stations on the F, including blazingly bright orange tiles and minimalist shapes. The stations feature high ceilings, resembling the metro in Washington, D.C. Blue tiles were also hung throughout the Wall Street No. 4 and 5 station, and in a strange touch, transit added an old token booth and ticket chopper in the entrance.

“It was kind of silly,” Robins said.

Sleek new stations
At the new South Ferry station, and the future Second Avenue subway and No. 7 line extension stations, transit is emphasizing a clean, sleek look that is modern and easy to clean, Kunoff said. White is now the standard color for tiles, as it reflects light and makes for brighter stations that are more energy-efficient. They are also trying to install the least amount of columns, as it helps with passenger flow, she said.

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A new subway bench?
NYC Transit officials are weighing whether to scrap the standard wood bench and opt for the system’s first stainless steel seats for the Second Avenue Subway and No. 7 extension stations. Designers are having a vigorous debate between the two models, with some viewing the steel as cold, while others blasting the wood as unhygienic, Kunoff said.

In coming months, officials will install prototypes of the two competing benches at an undisclosed station to get the public’s feedback, she said.

It’s not the first time that transit has experimented with seats -- funky orange benches were installed at the Jamaica-Van Wyck station in Queens, and the system also used plastic, metal and stone in the 1960s.