Hundreds of excited eyes flock to the side of the Ann Richards Bridge in Austin every summer. Once the sun sets, the jaw-dropping sight will soon blow them away. If you haven't seen Austin's unique attraction, dart over to the South Congress Bridge in the evening. This amazing experience of one of America's greatest sights.

The Ann Richards Bridge on South Congress is more than just a beautiful sight.

Kayaks float leisurely across Lady Bird Lake and yogis practice their downward-facing dogs along the shore. The picturesque views aren't what attract 100,000 spectators to the side of the bridge every year, however.

It's also home to North America's largest urban bat colony.

Every sunset between March and December, tourists flock to the sides of the bridge to catch a glimpse of these stunning creatures. Just as dusk sets in, these bats fly out from under the bridge to feed.

These bats are amazing animals.

The bridge is full of pregnant Mexican free-tailed bats. The newborns (referred to as pups) are a third of the mother's bodyweight. For a little perspective, that would be like a human giving birth to a 40 pound child!

The mothers can control their gestation period, so all of the bats give birth at the same time. When all of the pups are born, there are 1.5 million of them living under the Ann Richards Bridge!

It wasn't always this way.

Austin has always had a bat population, but the city didn't pay much attention to them until about 35 years ago. While expanding the South Congress Bridge in 1980, engineers added deep crevices at the bottom. Nobody knew they were building luxurious bat condominiums until 1.5 million of them showed up years later!

At first, people in Austin wanted to get rid of these winged creatures!

A huge "Eradicate the Bats!" campaign swept through the city in the early '80s. Austinites feared rabies and other infectious diseases. Thankfully, Merlin Tuttle from Bat Conservation International educated the city about these mammals. If Mexican free-tailed bats ever did contract rabies, they would immediately become paralyzed. Unless you pick up a bat off the ground, there's no chance of catching rabies!

Now, Austinites celebrate the bats every year.

The cloud of bats leaving the Ann Richards Bridge are nothing short of stunning, but that's not the only reason why Austinites love them. These bats eat between 10,000-20,000 pounds of mosquitos a night! Every Summer, the city of Austin throws Bat Fest and happy revelers flock to the bridge for adrenaline-pumping live music.

These winged creatures are part of Austin's identity.

Today, the bat bridge is a huge tourism destination. These cute flying mammals help generate ten million dollars of tourism revenue every year.

Have you experienced the phenomenon of this Austin bridge?