From underwater hotels to sprawling mansions, there are plenty of unique destinations across the United States that make for great, off-the-beaten path vacations or day trips. Here are five unusual destinations to visit in the U.S. that are definitely worth your time.

Coral Castle — Miami, Florida

Carved sculptures amid greenery at the Coral Castle near Miami
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We have one man to thank for the incredible experience that is the Coral Castle in Miami, Florida. Ed Leedskalnin spent 28 years carving this fascinating monument. He worked only at night and used his own tools to carve 1,100 tons of coral.

He created his masterpiece as a tribute to the woman he considered to be the love of his life, Agnes Scuvst. Ed and Agnes were engaged in Latvia, but she told Ed she couldn't go through with the marriage just one day before the wedding. She was invited to see the monument several times but never made the trip.

There is also an air of mystery surrounding the castle. Nobody ever saw Ed working on it, leaving many to wonder how a man who was barely five feet tall and weighed only 100 pounds could have possibly moved and carved all that coral. Legends speak of "reverse magnetism" and "supernatural abilities." Leedskalnin stated that he simply understood the laws of leverage.

Winchester Mystery House — San Jose, California

Front gardens and face of Victorian mansion
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The Winchester house in San Jose, California, is an architectural marvel that was once inhabited by Sarah Lockwood Pardee Winchester, who is the widow of William Wirt Winchester and thus the heiress to the Winchester Repeating Arms Fortune. Sarah moved from the home she shared with her husband and infant daughter in New Haven, Connecticut, to the eight-bedroom farmhouse in San Jose after they both died.

The home was one continuous renovation project that only ended when Sarah died in 1922. Nobody knows what compelled Sarah to work on the home, or why she added odd elements to the house such as a set of stairs that lead to nowhere.

Today, you can enjoy a tour of Sarah Winchester's former residence. You can also dine on-site as well.

Fenelon Place Elevator Company — Dubuque, Iowa

Little elevator car riding up the steepest and shortest railroad in the world
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Take a ride on the most unique elevator in the country when you visit the Fenelon Place Elevator Company in Dubuque, Iowa. This outdoor elevator is more of a railway than an elevator and is described as the steepest railway in the world. It's also the shortest, measuring only 296 feet long. However, in this short stretch, you'll be taken 189 feet up, from Fourth Street to Fenelon Place.

From the top, you'll have a view of the Mississippi River. The big draw, though, is that you'll be able to see three states from observation decks at the top: Iowa, Wisconsin, and Illinois.

It was originally constructed in the 1880s, back when the town of Dubuque would shut down at lunchtime and workers would have to make the long trek up the incline for their midday meal. Former mayor and businessman J.K. Graves constructed it as his personal cable car. Eventually, he gave rides to others who lived in the bluffs and worked in the city.

Today, the elevator is more of a tourist spot than a means of regular transportation. Visitors can take a ride from April 1 through November 30, however.

Jules' Undersea Lodge — Key Largo, Florida

Dock at Key Largo, Florida
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This one isn't for the faint of heart, but it is ideal for avid scuba divers. Jules' Undersea Lodge in Key Largo, Florida, is just that — under the sea. Guests have to scuba dive to get to their rooms, which are 30 feet underwater.

You don't have to stay overnight to visit the lodge, however. You can get day passes to swim in the lagoon, and if nobody is scheduled to stay the night, then you can look into the windows of the lodge. If you're a pro diver, book a room and stay the night.

Antelope Canyon — Arizona

Walls and sand of Antelope Canyon
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Antelope Canyon is natural wonder known for its wavy rocks that give off a mystical appearance. These naturally formed rocks are the result of millions of years of water and wind erosion. The rock formations now look like corkscrews, which is why the canyon is sometimes referred to as Corkscrew Canyon.

Unlike other national parks in the U.S., you need a reservation to go to Antelope Canyon. There are several tour companies in the area that can help you schedule a tour, though. Visit the Navajo Parks website to find a reputable tour guide for your trip. And don't forget to pack your camera.