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I’ve been fascinated by AT&T’s old Long Line towers since childhood, but I only started writing about them a little over a year ago. Since then, a few people have asked how to tell them apart from cell phone towers or other types of communications infrastructure. There are some unmistakable clues to spot them!

Before cell phones became a part of everyday life, AT&T’s Long Lines network was the backbone of long-distance communication. Even though the program was discontinued over forty years ago, nearly a hundred of its towering relics still rise above the landscape across Indiana. You’ve probably even driven by one without even noticing it! Here’s how you can be sure.

1- Horn antennae

I first noticed Long Line towers on family drives to Fort Wayne, recognizing them by their unique appearance long before I knew their name or what they were used for. To my young eyes, they looked like ordinary radio towers- that is, except for their enormous height and strange, shell-like structures perched at the top.

It turns out those shell-like structures were KS-15676 horn antennae designed to transmit and receive microwave signals between towers. Their distinctive shape, along with the rounder SHX10A antennae often added later, are key indicators that the tower you’ve spotted was once part of the Long Lines network.

2- Concrete monoliths

AT&T’s earliest Long Line towers were concrete to shield the horn antennae and provide security. If you’re driving around rural Angola, Goshen, LaGrange, LaPorte, or Valparaiso and come across a boxy, concrete behemoth, chances are you’ve stumbled across a Long Line Tower. AT&T’s first commercial path connected New York and Chicago, and the path went smack-dab through northern Indiana.

3- Tall guyed or self-supporting towers

I’ve visited sixty-four Long Line towers and sites as I write this. Sadly, only about a third still retain their original antennae. While the early concrete towers are easy to recognize without them, identifying the metal lattice versions can be much trickier when they’re naked! Fortunately, Long Line towers only came in two flavors around these parts: self-supporting and guyed. Generally triangular in profile, self-supporting Long Line towers measure anywhere from 150 to 350 feet tall. That’s far larger than a cell phone tower.

Guyed towers were often built later than their self-supported counterparts. They shoot straight into the sky and are stabilized by a web of wires. Because of their narrow profile, they seem extraordinarily tall: many rise to three hundred feet or more! Knowing about both flavors of steel Long Line towers might not help much in differentiating one from a typical radio mast aside from by size, but it’s valuable context when combined with other context clues.

4- Brackets and support systems

It might not seem like it from ground level, but horn antennae are massive- think minivan sized! Their dimensions and weight meant they couldn’t simply be bolted onto a tower like smaller gizmos and doodads. Instead, the heavy-duty devices required specialized brackets and support structures to keep them secure. Because of that, self-supported towers often sport distinctive shelves.

Guyed Long Line towers also featured brackets to mount their horn antennae, but they generally took a triangular shape. So far, I’ve only encountered two guyed towers with their horn antennae intact. I’m excited to see if there are more in the southwestern part of the state I haven’t visited yet.

5- Overbuilt infrastructure

Most of AT&T’s Long Line towers were decommissioned and sold around the year 2000. Many were purchased by management companies that now lease them to local or regional communication networks that installed their own equipment. If you spot a massive tower that matches all the previous criteria but only carries a few cells or a microwave drum, it’s probably a relic of the Long Lines era. Modern communication systems don’t require the heavy-duty infrastructure needed to support the old horn antennas, and the mismatch is a dead giveaway.

6- Concrete “Bunkers”

Every metal Long Line tower I’ve visited is accompanied by a concrete “bunker” that once housed important networking equipment. Often, the secure facilities are protected by barbed-wire fences and heavy, steel doors. While most communication towers include some type of shed or shack at their base, a particularly robust version is one more indicator that you’ve stumbled across an old Long Line tower.

Things like horn antennae, concrete or steel structures (self-supporting or guyed), support systems, bunkers, and overbuilt infrastructure are great clues, but they’re not the whole story when it comes to identifying old Long Line towers. Still, recognizing those features can make spotting them in the field much easier. It certainly does for me! If you’re really interested, though, and ever unsure, you can always check out my Long Line map. I update it with every new tower I visit.