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Two neighbouring cenotes, the 'two eyes', about 20 km north of Tulum, run by the local ejido as a park and the entrance to a flooded cave system explored since 1987 and now part of Sac Actun. Visitors snorkel in the clear water under the cavern roof; divers follow lines into the caves.

A cenote in the centre of Valladolid, a few streets from the main square, in a partly collapsed cavern with stalactites on its overhanging roof. A stairway cut into the rock leads down to the dark water, once the town's water source; the town takes its old Maya name, Zací, from the settlement here.

The parish church on the south side of Valladolid's main square, Parque Francisco Cantón, rebuilt in 1706 to face north after the earlier church was desecrated and demolished. Its white facade with two bell towers looks over the square.

A Franciscan church and convent in the Sisal quarter of Valladolid, built from 1552, among the oldest in the Yucatán. Its fortress-like church, cloister and gardens with a cenote and a waterwheel can be visited, and a light-and-sound show is projected on the facade in the evening.

A cenote about 4 km north-west of Tulum on the road to Cobá, part of the Sac Actun cave system. Wooden steps lead down to clear pools under rock overhangs with stalactites, where visitors swim and snorkel with turtles, and divers enter the flooded caves.

A walled Maya city on 12-metre cliffs above the Caribbean, a port for Cobá that flourished between the 13th and 15th centuries and was still inhabited when the Spanish arrived. Inside the wall stand El Castillo on the cliff edge, the Temple of the Frescoes and the Temple of the Descending God, with a beach below.

A white-sand beach with palm trees about 1 km south of the Tulum archaeological site, at the start of Tulum's hotel zone. From the water the ruins on the cliff to the north can be seen; beach clubs and public access points line the sand.

The ruins of a Maya city about 40 km west of Valladolid, beside the village of Pisté, a regional capital from about AD 600 to 1200. The stepped pyramid of Kukulcán (El Castillo), the Great Ball Court, the Temple of the Warriors, the round observatory El Caracol and the Sacred Cenote are spread over a wide area.

A round open cenote near Pisté and Chichén Itzá, about 37 km west of Valladolid, part of the Ik Kil archaeological park. Carved steps lead down to the water some 26 metres below ground level, with hanging roots and vines falling from the rim; visitors swim in it.

The Denver Museum of Nature & Science is a natural history and science museum in Denver's City Park, founded in 1900 as the Colorado Museum of Natural History and opened in 1908. Its halls cover dinosaurs and prehistoric life, wildlife dioramas, gems and minerals and space science, and the building also houses the Gates Planetarium and a large-format film theatre.

Denver Zoo, now run as the Denver Zoo Conservation Alliance, is an 80-acre (32 ha) zoo in City Park, founded in 1896. Its Bear Mountain was one of the first zoo enclosures in the United States built without cages, and areas such as Toyota Elephant Passage, Predator Ridge and Primate Panorama hold animals from around the world.

Denver Botanic Gardens is a botanical garden on York Street, beside Cheesman Park, run with the City and County of Denver on 24 acres (10 ha). It has themed gardens with plants from around the world, the Shofu-en Japanese garden, water-lily pools, a children's garden and the Boettcher Memorial Tropical Conservatory, a domed glasshouse of tropical plants.

The Cathedral Basilica of the Immaculate Conception is the cathedral of the Roman Catholic Archdiocese of Denver, at Colfax Avenue and Logan Street. Built from 1901 to 1911 in the French Gothic style to designs by Leon Coquard, it has two 221-foot (67 m) spires, altars of Carrara marble and stained-glass windows. It became a minor basilica in 1979.

The Colorado State Capitol in Denver houses the Colorado General Assembly and the governor's office. Designed by Elijah E. Myers and built of Colorado granite between 1886 and 1901, it has a dome covered in gold leaf. Visitors can walk through the building on weekdays, and guided tours climb to the dome's observation area.

The Denver Art Museum is an art museum in the Civic Center of Denver, with a collection of more than 70,000 works from around the world, including American Indian art and art of the American West. Its campus joins the Martin Building by Gio Ponti (1971) and the angular, titanium-clad Hamilton Building by Daniel Libeskind, opened in 2006.

The Denver Mint is a branch of the United States Mint that has struck coins since 1906; its coins carry the mint mark D. Its stone building on West Colfax Avenue, near the Civic Center, was begun in 1897 and still produces circulating and commemorative coins. Guided tours explain the mint's history and how coins are made.

Elitch Gardens is a theme and water park in downtown Denver, near the South Platte River. It was founded in 1890 by John and Mary Elitch in northwest Denver and moved to its present site in 1995. It has roller coasters, family and children's rides, a water park with slides and pools, and a hand-carved carousel from 1928.

The Downtown Aquarium is a public aquarium with a restaurant beside the South Platte River near Interstate 25. Built as Colorado's Ocean Journey, it was bought by Landry's in 2003 and reopened in 2005. Its tanks hold about a million US gallons and more than 500 animal species, including a shipwreck exhibit with sharks and a stingray touch pool.

One of the earliest and longest-inhabited Maya sites on the east coast of the Yucatán Peninsula, about 20 km south of Tulum on the edge of the Sian Ka'an reserve, occupied from about 350 BC into the 16th century. Its steep Castillo rises from the forest, and a boardwalk leads to the Muyil lagoon.

A protected area of tropical forest, mangroves, lagoons, savanna and coral reef south of Tulum, established in 1986 and a UNESCO World Heritage site since 1987. Boat trips cross its lagoons and the channels the Maya dug, and the road through it runs to the fishing village of Punta Allen.