Hovenweep National Monument
Ancestral Puebloan towers on the Utah-Colorado border, Gold Tier dark sky — and Hovenweep Castle's masonry is aligned to mark the solstices.
Cajon Mesa · Great Sage Plain · Four Corners
National Monument 785 acres 5,400 ft high point Est. 1923 National Park Service Dark Sky Park · Gold Tier
Overview
Hovenweep is 785 acres in six pieces, scattered over twenty miles of the Utah-Colorado line, and there is almost nothing there: a small campground, a ranger station, and the towers. They were built between roughly AD 900 and 1350 by Ancestral Puebloan people, in square and round and D-shaped masonry set right at the heads of canyons, and they are still standing. The name is a Ute and Paiute word usually rendered 'deserted valley'. What makes this a dark-sky park is not scenery — it is emptiness, and a very low population density in every direction. But what makes it worth writing about is that the builders were already doing this: the alignment of Hovenweep Castle works as a solar calendar, port-holes and wall angles marking the solstices and equinoxes for people whose farming depended on knowing exactly when the year turned. The sky over Hovenweep is certified now. It was being used a thousand years ago.
Getting in
When to go
Best: Apr, May, Sep, Oct
Spring and autumn. Summer is very hot with no shade; winter is cold but clear and empty, and the nights are long.
Safety & conditions
Activities
Hiking
Short loop trails around each unit — the two-mile Square Tower loop is the one nearly everyone walks. The outlying units require dirt-road driving and a map.
Season: Spring and autumn. Summer is brutally hot and shadeless.
Stay on the trails and off the walls. These are standing structures a thousand years old.
Stargazing
Gold Tier, certified 2014, and the emptiest sky in this corpus by population density. NPS measured Bortle 3 in 2005. The towers are the point: photographing the Milky Way over Hovenweep Castle is the shot everyone comes for, and it is a shot of a solar observatory under the sky it was built to read.
Season: Year-round; new-moon windows best. Spring and autumn nights are the most comfortable.
The monument is remote enough that the drive out at night is a real consideration. There is no fuel and no service.
Camping
A small first-come campground at the Square Tower unit — thirty-odd sites, no hookups.
Regs: First-come, first-served.
Wildlife & Paleontology
Modest. This is a place you come for the ruins and the sky.
Night Sky
Dark Sky Park Gold Tier Certified 2014 Bortle 3 21.62 mag/arcsec² across 1 site mag 6.6 limit
Bortle 3, and both the NPS and the volunteer observer agree on it. The domes are named and measured by eye in the application: 'Looking east and southeast toward Cortez/Farmington, the light dome extends up about 10 degrees, and to the south and Bluff the dome is a more modest 5 degrees.' The NPS photometry also picked out 'numerous unshielded outdoor lights along the horizon from azimuth 160-240 degrees' — individual porch lights on the Great Sage Plain, visible from inside a national monument. What moves the number: moon, haze, and the slow growth of Cortez and Farmington.
What the sky does here
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Typical
Bortle Class 3: Civilization Beyond the Rim
Under a Class 3 sky, the Milky Way remains strong while a faint light dome or other distant glow can reveal the direction of civilization. The wilderness feels real, but home remains perceptible as a small signal beyond the horizon.
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Only when
Bortle Class 2: The Wilderness Has Its Own Light
On a moonless night with the Milky Way up and the domes of Cortez and Farmington below the eastern horizon — the volunteer observer wrote that it "showed good detail down almost to the horizon."
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Only when
Bortle Class 4: The Contested Sky
Looking east and southeast toward Cortez and Farmington, where the dome climbs about ten degrees off the horizon, and along the southern arc where the NPS photometry picked out unshielded porch lights on the plain.
Geology
Shallow canyons cut into a high mesa, with seeps at the canyon heads. The towers were built at those seeps, from the sandstone lying around them — the water is the whole reason for the settlement.
Province: Colorado Plateau — Great Sage Plain / Cajon Mesa
Rock types: sandstone
Major formations
Also present: Burro Canyon Formation
Ecology
Biomes: Colorado Plateau semi-desert shrubland; pinyon-juniper woodland; sagebrush
Flora
- Utah juniper and pinyon
- sagebrush and rabbitbrush
- canyon-head seep vegetation
Fauna
- mule deer
- coyote
- collared lizard
- canyon wren
Dry, hot in summer, and quiet. The canyon-head seeps concentrate what life there is — as they did for the people who built here.
History
Hovenweep sits within the ancestral homeland of the Pueblo peoples — the descendants of the people who built these towers live in the Pueblos of New Mexico and Arizona and at Hopi today — and within the homelands of the Ute and Navajo nations, one monument unit being on Navajo Nation land. This is a living relationship, not a closed chapter. The towers were built during the Pueblo II and III periods, roughly AD 900 to 1350, at the heads of canyons where the springs are. The alignment of Hovenweep Castle functions as a solar calendar, marking the solstices and equinoxes — a farming people's instrument for knowing when the year turned. The monument was proclaimed in 1923.
Modern issues
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Unshielded rural lighting
Status: ongoing
NPS all-sky photometry picked out numerous individual unshielded outdoor lights along the southern horizon, from azimuth 160 to 240 degrees. Not a city dome — porch lights on the Great Sage Plain.
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Cortez and Farmington growth
Status: watch
The application measures their combined dome at about ten degrees above the eastern and southeastern horizon.