Since 1972, UNESCO has annually declared World Heritage Sites to identify and preserve humankind's most significant natural, historic and cultural attractions. The 890 designated spots (to date) met rigorous selection criteria assessed by international judging panels, a process even more complex than Olympic bids. The United States abounds in what Time magazine once dubbed "the Oscars of the environment” from mountains to monuments, lakes to landscapes -- all of these wonders made the list for their must-see, iconic status. The following attractions, however, comprise the top ten most-visited across the nation. Which World Heritage Site ranks number one? Read on: You might be surprised!"

Over millions of years, submarine eruptions thrust molten rock like restless spirits through the earth's crust, forming volcanic peaks which emerged from the Pacific and formed the Hawaiian islands. This site on the Big Island—now the 10th most visited World Heritage Site in the U.S.—contains two of the world’s most active volcanoes, Mauna Loa (13,677 feet high) and constantly glowing, growing Kilauea (4,091 feet). The dramatic landscape, easily viewed from the 11-mile Crater Rim Drive, constantly changes as fresh lava flows create fanciful formations. Indeed, since 1983 Kilauea’s near-continuous eruptions have added over 568 acres of new shoreline, covering 8.7 miles of highway with lava as deep as 115 feet. The park, spiraling from desert to tropical rainforest, also serves as refuge for the islands’ endemic flora and fauna including giant fern forests and the endangered Honu’ea (hawksbill turtle).

Annual Visitors: 1,612,246

UNESCO called this soaring monument to freedom, whose full name is Liberty Enlightening the World "a masterpiece of the human spirit." Guarding the entrance to New York Harbor, this 151-foot statue of a woman holding a torch and book (representing the Declaration of Independence) was a gift from France to commemorate the centennial of American independence in 1886. French sculptor Frederic-Auguste Bartholdi crafted the statue in Paris, using the repousse` technique of hammering thin copper sheets over large wooden forms, which were then attached over a steel framework designed by Alexandre-Gustave Eiffel (yes, of the tower fame).

Disassembled and shipped stateside in 214 crates in 1885, it would soon welcome millions of immigrants, who were processed at nearby Ellis Island. Lady Liberty endures as a shining beacon to such ideals as democracy, peace, opportunity, and human rights.

Annual Visitors: 1.67 million

The 367 surveyed miles of Kentucky’s aptly named Mammoth Cave National Park, comprising the world’s longest known cave system may just be the tip of the iceberg in what’s affectionately called the world’s largest hole in the ground, a tourist attraction since 1816. Stephen Bishop, the slave who gained fame as a guide and explorer here in the mid-19th century called the cave a "grand, gloomy and peculiar place," thanks to its awe-inspiring vast chambers and labyrinthine network that over time briefly served as a tuberculosis hospital, underground hotel, even church. Subterranean geologic features include stalactites, stalagmites, helictites, travertine dams, and various gypsum formations. Its passageways teem with more than 130 documented species of flora and fauna, including eyeless and un-pigmented cave dwellers such as fish, crayfish, beetles, crickets, and of course, bats. The park also preserves part of south-central Kentucky’s hilly, scenic, wildlife-filled Green River Valley, dancing around meadows stippled with sinkholes, snaking beneath bluffs blanketed with tulip poplars, beech, hickory, dogwood, and black oak trees.

Annual Visitors: 2 million

Redwood National Park encompasses a 40-mile-long region of coastal mountains bordering the Pacific Ocean north of San Francisco. It protects a magnificent forest of redwoods, the tallest and arguably most impressive trees in the world: Some vault 30 stories high and have thrived for millennia. The marine and terrestrial life are equally remarkable, in particular the sea lions, bald eagles, and endangered California brown pelican. Among the highlights, whether driving or hiking under the imposing canopy, is the 4,000-year-old Fraternal Monarch, site of an old house carved into its “basement” (hollowed by a forest fire eight centuries ago). There are more than 300 developed campsites in the three state parks (Prairie Creek, Del Norte, and Jedediah Smith) comprising the national park, shoreline trails and beaches, and ranger-guided tours.

Annual Visitors: 3 million

Located in northwest Washington State, Olympic National Park is renowned for its diverse ecosystems. Glacier-clad peaks interspersed with extensive alpine meadows plunge to fog-shrouded coast, surrounded by temperate rainforest. Eleven major river systems drain the Olympic Mountains and the park is known for its 73-mile-long coastline one of the longest undeveloped stretches of coastline in the contiguous United States. As you might expect, the wildlife here is spectacularly rich—keep your eyes open for endangered spotted owls, marbled murrelets, and bighorn sheep. Just offshore, whales, dolphins, sea lions, seals, and sea otters cavort in the Pacific. Roads access the park’s periphery, but Olympic’s heart is wilderness: a primeval sanctuary for humans and wild creatures alike.

Annual Visitors: 3.3 million

In 1872 President Grant established a vital precedent for environmental conservation by enacting Yellowstone as the world's first national park. Covering nearly 3,500 square miles in Wyoming, Montana and Idaho, the park, formed by violent volcanic and glacial activity, boasts bountiful geothermal features (which helped paint canyon walls in near-psychedelic colors). The most famous, of course, is Old Faithful Geyser, rocketing up to 184 feet every 60-100 minutes, but actually thousands of geysers and hot springs bubble, belch and sigh beneath Yellowstone. The park is filigreed with pristine rivers, lakes (136-square-mile Yellowstone is North America’s largest high-altitude body of water), and sparkling cascades tumbling hundreds of feet into the Grand Canyon of the Yellowstone. Abundant wildlife is on display alongside Nature’s artistry: pronghorn sheep, bison, grizzlies, more than 1,000 gray wolves, and elk.

Annual Visitors: Nearly 4 million

California’s Yosemite National Park is a glorious living laboratory of hydrology, geology, glaciology, seismology, and more. Its “hanging” valleys, waterfalls, cirque lakes, polished domes, moraines and U-shaped valleys provide an excellent overview of how glaciations fashioned granite relief. The 1,189-square-mile park contains thousands of lakes and ponds, a high concentration of waterfalls (including 2,425-foot Yosemite Falls, North America’s highest cascade), 800 miles of hiking trails, and 350 miles of roads. The most popular part of the park is the seven-square-mile Yosemite Valley, which renowned photographer Ansel Adams called, “…a glitter of green and golden wonder in a vast edifice of stone and space.” Some of America’s most recognizable landscape images are there, including the imposing granite cliff El Capitan, Cathedral Spire, and The Lost Arrow pillar. Small wonder adrenaline junkies from rock climbers to backcountry skiers flock here.

Annual Visitors: More than 4 million

Independence Hall’s significance lies not just as a superb example of British colonial architecture, but as the literal birthplace of the United States of America. The Declaration of Independence, a radical document for its time, was signed here in 1776, setting the stage for the Revolutionary War and eventual founding of the American nation. Here the Articles of Confederation uniting the thirteen colonies were ratified in 1781 and the Constitution codifying the nation's basic laws adopted in 1787. Today, visitors can tour the rooms of the grand Pennsylvania Commonwealth (colony) state house where such historical giants as Jefferson and Franklin debated, their words and ideals thundering across the centuries. In tandem with the iconic cracked Liberty Bell across the street, the site still eloquently, stirringly resounds with the Founding Fathers’ conviction that "all men are created equal."

Annual Visitors: 1.67 million

A national park since 1919 and one of 28 finalists in the recent New Seven Wonders of Nature campaign, the powerful, inspiring Grand Canyon qualifies among the earth's greatest ongoing geological spectacles. For the last 5-6 million years, the Colorado River has slowly sliced through the layers of rock comprising the Colorado Plateau. The river and its tributaries conspired with weather’s erosive forces to sculpt a spectacular gorge one mile deep and up to 18 miles wide along a 277-mile stretch. The canyon walls’ perfectly preserved colorful strata recount the story of the earth's evolution dating back nearly 2 billion years, providing invaluable geologic evidence of our planet’s origins. The South Rim is more accessible, but the rugged, less trafficked North Rim (1,000 feet higher) also provides overlooks and miles of walkways that take in the canyon’s soaring, plunging grandeur.

Annual Visitors: 4.43 million

The Great Smoky Mountains are among the planet’s oldest ranges, formed 200-300 million years ago. Encompassing more than 800 square miles straddling Tennessee and North Carolina, this exceptionally lovely, biologically diverse park is home to more than 3,500 plant species, including almost as many trees (130 natural species) as in all Europe. Many endangered fauna also reside here, including probably the world’s greatest variety of salamanders. Over 10,000 species have been documented yet scientists believe an additional 90,000 species may reside here. Mountains, glaciers, elevation shifts (875 to 6,643 feet), and varied weather create this wondrous diversity. The park also preserves the rich Southern Appalachian timeline and cultural tapestry, from the prehistoric Paleo Indians to European settlement in the 1800s to early 20th century loggers. Various edifices and artifacts, such as barns, grist mills, and homes, tell tales of the peoples who once called these mountains home.

Annual Visitors: 9.04 million