As the National Park Service celebrates its 100th anniversary this August with a series of activities and events taking place across the continent, including National Park Week taking place from 16-24 April during which visitors can explore the dedicated landscapes under free admission, take a look at Colorado's four stunning national parks by numbers.

Mesa Verde National Park and World Heritage Site

The Mesa Verde World Heritage site is a preserved prehistoric settlement of the Ancestral Puebloan culture, which lasted for almost 900 years from c. 450 to 1300. According to the National Park Service (NPS), 24 American Indian nations consider Mesa Verde their ancestral home. This is the USA's premier archaeological park and the first National Park dedicated to preserve the works of man; it was established by Theodore Roosevelt in 1906 for this purpose.

The plateau in southwest Colorado sits at an altitude of more than 2,600 meters and Mesa Verde National Park is home to nearly 5,000 known archaeological sites; including pueblos, masonry towers, farm structures and 600 cliff dwellings, such as the largest: Cliff Palace, which was home to approximately 100 people who lived among its 150 rooms and 23 kivas (ceremonial structures). Both NPS Ranger-led and self-guided tours are available to five of the dwellings. Additionally, there are more than 20 mesa-top sites visitors can access independently.

Rocky Mountain National Park

The third most popular park in 2015 with 4.2 million visitors, Rocky Mountain National Park follows the Continental Divide between the Coloradan towns of Estes Park and Grand Lake. It is the USA's highest altitude National Park, with 415 square miles of hiking and biking trails along 60 peaks that rise above 12,000 feet. One third of the park is tundra (above the altitude where trees can grow), however, there's only one 'Fourteener' inside the park's boundaries: Longs Peak at 14,259m, which is the 15th tallest of Colorado's 58 'Fourteeners'.

Activities for visitors abound as the headwaters of the mighty Colorado Rover start here, making it one of the best whitewater rafting destinations in the nation. Rocky Mountain National Park also boasts 300 miles of hiking trails, 150 lakes and 450 miles of streams – perfect for a cooling dip. A famed route for exploration is Trail Ridge Road, which peaks at an altitude of 12,183 feet and is the highest through-road in the USA.

Great Sand Dunes National Park & Preserve

Located where the Sangre de Cristo Mountains buckle inward north of Alamosa, the Great Sand Dunes have been building and sifting for years – the result of the San Luis Valley's unique wind patterns. This sandbox of epic proportions measures 30 square miles and the dunes are the tallest in North America, with the tallest, Star Dune, rising 750ft. Visitors can hike the three miles upwards from the trailhead to Star Dune; sandboard and sand sled down throughout the park, as well as all the time keeping an eye open for one or two of the six known insect species that are found only within the park. The Great Sand Dunes Tiger Beetle is one such example.

Black Canyon of the Gunnison National Park

Perhaps the most overlooked of Colorado's National Parks, Black Canyon, so named because the walls are often shrouded in shadows making them appear black, is located between Gunnison and Montrose and is ideal for scenic drives along the Gunnison River below. Carved out over 2 million years ago and at 48 miles long, the Black Canyon of the Gunnison drops 2,722ft at its deepest; while its greatest width is 1,100ft across, its narrowest span is just 40ft.

The park offers stunning geological features, including the Painted Wall – so-called for its distinct, veiny white streaks are pegmatite, a type of granite comprised of quartz, feldspar and mica – which rises 2,250ft up from the river and is Colorado's tallest cliff, Chipeta Falls, the Curecanti Needle and Pioneer Point.

In addition the state of Colorado is home to eight National Monuments: Browns Canyon National Monument; Canyons of the Ancients National Monument; Chimney Rock National Monument; Colorado National Monument; Dinosaur National Monument; Florissant Fossil Beds National Monument; Hovenweep National Monument and Yucca House National Monument.

Colorado is a year-round destination offering unparalleled adventure and recreational activities, an abundant arts scene, Western heritage, distinctive cuisine and 25 renowned ski resort areas. The state's scenic landscape boasts natural hot springs, the headwaters of four major rivers, numerous peaceful lakes and reservoirs, 11 national parks and monuments and 58 mountain peaks that top 14,000 feet, known as 'Fourteeners'.