History about a century in the making: the Second Avenue Subway opened to the public at noon Sunday.

"We moved here two months ago, and I told my friends, 'Oh, you know, the new subway was going to be open,'" one local resident said. "They don't believe me! They say, 'Oh, you know, it'll take 100 years, not two months.' Now it's happens, oh my God! We feel very lucky."

Many people have come to the station at 72nd Street and 2nd Ave. since the early morning.

The $4.5 billion line runs 1.5 miles from 63rd to 96th Streets.

Q trains are now stopping at three new stations at 72nd, 86th, and 96th Streets on the Upper East Side.

The new line has a connection at the existing F train station at 63rd Street.

The Second Avenue Subway is expected to help ease congestion on the Lexington Avenue line — the 4, 5, and 6 trains, which are the most congested in the world — for 200,000 riders a day.

"I think it will make a difference. I mean, for the people who've been waiting for this to be built for over 100 years, it's done," said MTA Chairman and CEO Thomas Prendergast. "We said we'd meet a date, and we did meet a date."

Paying customers can ride on New Year's Day until 10 p.m.

For the rest of the week, the line will run from 6 a.m. to 10 p.m. 24-hour service starts Jan. 9.

The Q train has been rerouted to the Second Avenue line and now runs between 96th Street in Manhattan and Coney Island in Brooklyn.

People in the area have hoped that the new line will shorten their commutes, and those living in the area say they are glad that the past ten years of construction and road closures are over.

"It was a pain because businesses were closing down due to the work, the street was a mess for ten years or so," one of the first riders said. "Now we have this amazing train."

"It's an engineering marvel, so we just decided to check it out," another straphanger said. "It's 100 years in the making. Hopefully in my lifetime they'll finish it."

Some people are also optimistic that the line will improve their neighborhood's property values.

Gov. Andrew Cuomo, who has been taking a victory lap for officially pushing the project's first phase into completion, gave riders Sunday the official invite into the station.

As usually jaded riders checked out the cavernous new stations, their subway cynicism faded amid the sparkle.

"We've been waiting for this for over 30 years, as far as I can remember, and it's just fantastic," one commuter said.

"Even on a delayed train, it was like everybody got their Christmas gifts," another said. "And if took them a little while to open it, they were going to stand there patiently inside the train."

The governor said 2,000 workers overall were involved in getting this first phase done.

Cuomo and Mayor Bill de Blasio took the inaugural ride on the Second Avenue Subway line Saturday night.

The next stage, phase two, would extend the line from 96th to 125th Streets. $1 billion has been set aside for initial planning work.

Work on the Second Avenue Subway line began in 1972, when Mayor John Lindsay and Gov. Nelson Rockefeller broke ground in East Harlem.

Three years later, the project was shelved, a victim of the financial crisis battering the city and state.

The line was formally proposed in the 1920s to run the length of Manhattan, one of three new north/south routes.