Subway enthusiasts marked a big milestone with a trip back in time.

Officials brought back the "train of many colors," which is made up of 100 vintage cars, to celebrate the 7 train's 100th birthday.

It rode from Grand Central Station to Corona at 2 p.m., the exact time the line went into service.

Another celebration was held at the Times Square Station, complete with birthday cake and balloons.

"The 7 line is a very picturesque route, and it deserves to have these cars, these Redbirds, Bluebirds, R-33 World's Fair Cars, R-33 cars, in general run on the line for such a special occasion," said one attendee.

"It's amazing to be here and celebrate," said another. "You can see the development it brought to Queens, the fact that it had a line that connected Queens and Manhattan. So it's exciting to see what can happen in 100 years of transportation."

The link between Manhattan and Queens first opened to the public on April 21, 1917.

Back then, the line had 11 stations and served an estimated 15,000 people per day. It now has 22 stations serving more than half a million daily riders.

It is also undergoing a $750 million renovation.