Walking the Old Seven Mile Bridge to Pigeon Key

The Bridge Flagler Built and the Island That Built It

"Two and a bit" miles of century-old roadway over open water, ending at a five-acre island where hundreds of men once lived and worked, the Old Seven Mile Bridge is one of the most memorable walks in the Florida Keys — and one that many visitors drive right past.

There are two Seven Mile Bridges in Marathon, running side by side. Almost everyone crosses the new one at highway speed, takes in the view, and keeps going toward Key West.

The old one is the interesting one. And you can walk on it.

Two Crews, Twelve Hours Each, Around the Clock

In 1905, Henry Flagler decided to extend his Florida East Coast Railway across open ocean to Key West — an ambitious project the press dubbed “Flagler’s Folly.” The Seven Mile stretch was one of its most challenging pieces.

Construction on this portion of the Overseas Railway ran from 1908 to 1912, with the men doing the work based on Pigeon Key, a tiny five-acre island beneath the bridge.

At the height of construction, roughly 400 workers were housed there, earning about $1.50 a day. Flagler was 75 when the project began and his health was failing, so the crews worked in two shifts — twelve hours on, twelve hours off. Work continued day and night.

The railroad was completed on January 22, 1912. Flagler, by then nearly blind from cataracts, rode the first train into Key West. He died the following year.

Hurricane, Highway and a Very Narrow Road

The railway ran for 23 years. Then, on Labor Day 1935, a devastating Category 5 hurricane struck the Upper Keys, destroying miles of track near Islamorada and claiming hundreds of lives. The railroad, already facing financial difficulties, never reopened.

The state purchased the right-of-way, laid a road deck over Flagler’s bridges and opened the Overseas Highway in 1938.

For the next 44 years, the Old Seven was the only way to drive to Key West. It was just 22 feet wide, with one lane traveling in each direction and no shoulder. Anyone who made that drive before 1982 probably remembers it.

The new Seven Mile Bridge opened in 1982 and took over vehicle traffic. The old bridge was eventually closed to cars, and after decades of exposure to the elements, it needed significant restoration.

A major rehabilitation project brought the historic span back to life, and in January 2022 the restored 2.2-mile section between Marathon and Pigeon Key reopened to walkers, runners, cyclists and anglers.

There is one particularly interesting detail to watch for as you walk: the rusted rails along the outer edge of the bridge are remnants of Flagler’s original railroad tracks. When the railway bridge was converted for automobile traffic, the rails became guardrails — and portions remain visible today.

Pigeon Key

The walk ends at Pigeon Key, and rather than turning around at the ramp, it is worth making the island part of your visit.

Historic buildings from the railroad era still stand here, along with a museum filled with Flagler-era artifacts and photographs. The island preserves an extraordinary piece of Florida Keys history — the place where the workers responsible for one of the most ambitious engineering projects of their time lived while the railroad was being built.

It is also simply a lovely place to spend a few hours. You'll find palms, picnic tables, a small beach area and clear water off the dock. Snorkeling is encouraged, so consider bringing your gear and making a longer afternoon of it.

Four Things Worth Knowing Before You Go

• Go early. Parking at the Marathon end of the Old Seven is limited and can fill quickly. An early start also means cooler temperatures for the walk.
• Prepare for the sun. There is virtually no shade on the bridge. Bring a hat, sunglasses, sunscreen and more water than you think you'll need — especially for the walk back.
• Bring snorkel gear. The clear, shallow water off the Pigeon Key dock adds an entirely different experience to the history tour.
• Consider bikes. The 4.4-mile round trip is a substantial walk in full sun but an easy bicycle ride. Bike rentals are available throughout Marathon.

One More Thing: Yes, That Bridge

If the Old Seven looks strangely familiar, there may be a reason.

The bridge has appeared on screen over the years, most famously in the 1994 Arnold Schwarzenegger film True Lies, where a section appears to be destroyed during the movie's climactic action sequence.

Don't worry — they didn't actually blow up the Old Seven. The explosion was created using a scale model. The bridge survived, and today you can walk right across it.

Where to Stay

Pigeon Key's first train leaves in the morning, and the bridge is especially beautiful in the softer early light. Staying in Marathon puts you close enough to enjoy the Old Seven without turning the experience into a long drive from either end of the Keys.