 Rough Trail to Gray s Arch. Red River Gorge, Kentucky, November 5, 1999.
 Forest below Gray s Arch. Red River Gorge, Kentucky, November 6, 1999.
 View from the top of Gray s Arch at morning. Red River Gorge, Kentucky, November 6, 1999.
 View from the top of Gray s Arch at morning. Red River Gorge, Kentucky, November 6, 1999.
 Rhododendron, fir and maples near Gray s Arch. Red River Gorge, Kentucky, November 6, 1999.
 Forest near Gray s Arch at morning. Red River Gorge, Kentucky, November 6, 1999.
 Forest near Gray s Arch at morning. Red River Gorge, Kentucky, November 6, 1999.
 Forest near Gray s Arch at morning. Red River Gorge, Kentucky, November 6, 1999.
 Forest near Gray s Arch at morning. Red River Gorge, Kentucky, November 6, 1999.
 Gray s Arch with rhododendron on foreground. Red River Gorge, Kentucky, November 6, 1999.
 Erosion of limestone near Gray s Arch. Red River Gorge, Kentucky, November 6, 1999.
 View of rock shelters from the top of Gray s Arch. Red River Gorge, Kentucky, November 6, 1999.
 Gray s Arch, view from rock shelters. Red River Gorge, Kentucky, November 6, 1999.
 Gray s Arch, view from rock shelters. Red River Gorge, Kentucky, November 6, 1999.
 A.S. on Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 View from Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 A tree with very big leaves on Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 A small maple on Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Pine forest on Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Unknown dwarf berries on Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Rhododendron in a canyon, view from Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Blueberry and rhododendron bushes on Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Erosion of a limestone rock at Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Multicolor maple leaves on Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Erosion forms of limestone in a rock shelter at Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Erosion forms of limestone on a rock shelter at Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 Tree roots and erosion forms on a limestone rock at Rough Trail. Red River Gorge, Kentucky, November 6, 1999.
 A.S. on Buck Trail. Red River Gorge, Kentucky, November 7, 1999.
 Buck Trail. Red River Gorge, Kentucky, November 7, 1999.
 Sheltowee Trail. Red River Gorge, Kentucky, November 6, 1999.
 Forest near Buck Trail. Red River Gorge, Kentucky, November 7, 1999.
 View from Pinch Em Tight Trail. Red River Gorge, Kentucky, November 7, 1999.
 View from Pinch Em Tight Trail. Red River Gorge, Kentucky, November 7, 1999.
 Oak forest near Pinch Em Tight Trail. Red River Gorge, Kentucky, November 7, 1999.
 View from Pinch Em Tight Trail. Red River Gorge, Kentucky, November 7, 1999.
 Mushrooms in moss at Buck Trail. Red River Gorge, Kentucky, November 7, 1999.
 Flowers on a stone at Buck Trail. Red River Gorge, Kentucky, November 7, 1999.
 Sheltowee Trail near Chimney Top Rock. Red River Gorge, Kentucky, November 6, 1999.
 View from Pinch Em Tight Trail. Red River Gorge, Kentucky, November 7, 1999.
 View of a canyon from Pinch Em Tight Trail. Red River Gorge, Kentucky, November 7, 1999.
 Bottom of a canyon, view from Sheltowee Trail. Red River Gorge, Kentucky, November 6, 1999.
 Limestone erosion forms at Koomer Ridge Trail. Red River Gorge, Kentucky, November 7, 1999.
 Bamboo brushes on the bottom of a canyon near Sheltowee Trail. Red River Gorge, Kentucky, November 6, 1999.
 A fungus (?) on a birch, Sheltowee Trail near Chimney Top Rock. Red River Gorge, Kentucky, November 6, 1999.
 Mushroom-like limestone erosion forms at Koomer Ridge Trail. Red River Gorge, Kentucky, November 7, 1999.
 Creeping fern among dry leaves and needles on Koomer Ridge Trail. Red River Gorge, Kentucky, November 7, 1999.
 Limestone rocks, view from Sheltowee Trail near Chimney Top Rock. Red River Gorge, Kentucky, November 6, 1999.
 View of canyon walls at evening from Sheltowee Trail near Chimney Top Rock. Red River Gorge, Kentucky, November 6, 1999.
 Tobacco farm near Slade, Kentucky, November 5, 1999.
 View of Wabash River from a trail to Fort Ouiatenon. Indiana, November 13, 1999
 Steel arch bridge across Brazos River, view from Waco Suspension Bridge. Waco, Texas, November 22, 2009
 Modern painting Triumphal Arch (1999) by Valeriy Lukka in Erarta Museum of Contemporary Art. Saint Petersburg, Russia, May 29, 2019
 Potholes Park, Fall Creek Gorge. The trip was organized by Purdue University International Center. Near Pine Village, Indiana, June 5, 1999.
 Rustic, three-arched stone bridge (often referred to as the Ruin Bridge or simply the stone arch bridge) in the "Russian Switzerland" area in Oranienbaum s Upper Park. Built from rough-hewn boulders to mimic a natural or ancient ruin, it harmonizes perfectly with the wild, rugged aesthetic of the Karasta River valley. The bridge spans a small ravine or tributary, surrounded by a golden forest of birch and maple trees that soften the stone s heavy appearance with delicate autumn foliage. Oranienbaum palace-and-park ensemble in Lomonosov (a suburb of St. Petersburg), Russia, October 13, 2025
 Inspecting a creek in Potholes Park (Fall Creek Gorge) by international students of Purdue University. Near Pine Village, Indiana, June 5, 1999.
 Overcoming a tub in a creek in Potholes Park (Fall Creek Gorge) by an international student of Purdue University. Near Pine Village, Indiana, June 5, 1999.
 A stone arch bridge of the Kristatelka River situated downstream from the "Adam s Head" sculpture. The bridge features a solid, polished masonry arch topped with a simple, functional black iron railing. Spanning a cascade of moss-covered boulders and small waterfalls, the bridge sits deep within the ravine, creating a secluded atmosphere amplified by the dense canopy of trees. Sergievka Park, Old Peterhof, west from Saint Petersburg, Russia, October 13, 2025
 Forest of Enfield gorge, from Rim Trail, in Robert H. Treman State Park. Ithaca, New York, November 2, 2005
 International students of Purdue University walking over rapids and tubs of a creek in Potholes Park (Fall Creek Gorge) near Pine Village. Indiana, June 5, 1999.
 Fallen sycamore tree in snow near Gorge Trail in Taughannock Falls State Park. New York, November 23, 2005
 Fall colors of Enfield gorge, view from Rim Trail, in Robert H. Treman State Park. Ithaca, New York, November 2, 2005
 Fall colors of Enfield gorge, zoomed, view from Rim Trail, in Robert H. Treman State Park. Ithaca, New York, November 2, 2005
 Entrance to Nahal Tseelim River Gorge, 2 miles north from Masada. The Middle East, January 20, 2001
 Rustic stone arch bridge, nestled deep within the Sergievka Park ravine. Built from rough-hewn granite blocks, the bridge was designed to look ancient and weather-beaten even when new, fitting the 19th-century romantic preference for melding architecture with wild nature. The bridge spans a small cascade of the Kristatelka River, where water tumbles over mossy stone steps, creating a soothing auditory backdrop to the visual serenity. The scene is framed by golden maples and fallen leaves that carpet the banks and settle into the stream s rocky bed, enhancing the secluded, fairy-tale atmosphere. Sergievka Park, Old Peterhof, west from Saint Petersburg, Russia, October 13, 2025
 Drying forest at Heritage Trail along Wabash River north from Lafayette. Indiana, September 11, 1999.
 A trail along Wabash River at Ross Hills Park 5 miles west from Lafayette. Indiana, October 30, 1999.
 Rough bark of winged elm (Ulmus alata) on Post Oak Trail in Lick Creek Park. College Station, Texas, November 27, 2020
 Wabash Street Bridge across Chicago River. Sun-Times Daily News, Wrigley and Equitable Buildings are behind the bridge. Chicago, November 22, 1999
 Stone arch of Ruins (1800-1803) near Slavyanka River one mile from Tiarlevo in Pavlovsk Park, suburb of Saint Petersburg. Russia, May 15, 2011
 A.S. at entrance to Nahal Tseelim River Gorge from Dead Sea, 2 miles north from Masada, view from a parking place. The Middle East, January 20, 2001
 Entrance to Nahal Tseelim River Gorge from Dead Sea, 2 miles north from Masada, view from a parking place. The Middle East, January 20, 2001
 Kathy Trail along Missouri River near Columbia, Missouri. October 23, 1999.
 Kathy Trail along Missouri River near Columbia, Missouri. October 23, 1999.
 Rocks along Missouri River, view from Kathy Trail near Columbia, Missouri. October 23, 1999.
 Rocks and bushes along Missouri River, view from Kathy Trail near Columbia, Missouri. October 23, 1999.
 Bushes on rocks along Missouri River, view from Kathy Trail near Columbia, Missouri. October 23, 1999.
 Steel arch bridge spanning Brazos River (Washington Street Bridge, built in 1901), from south-west. Waco, Texas, August 23, 2008
 A wall of the gorge in Taughannock Falls State Park. New York, November 23, 2005
 State Street Bridge across Chicago River. City Garage (?) and Blue Cross - Blue Shield Building are behind the bridge. Chicago, November 22, 1999
 A wooden double door set within a limestone portal at approximately Pikk 67 in Tallinn s Old Town. The door is framed by a round-arched limestone portal, a common feature in Tallinn s medieval Hanseatic architecture. The rough-hewn stone blocks (voussoirs) forming the arch are clearly visible where the plaster has fallen away, revealing the underlying construction technique. The surrounding wall features peeling stucco in shades of ochre and grey, exposing the limestone masonry beneath. This texture speaks to the building s age and the ongoing challenge of maintaining historic structures in the local climate. The door itself is made of diagonal wooden planks, a traditional style for utility or courtyard entrances in the Old Town. It appears to be a secondary entrance rather than a main portal for a wealthy merchant s house. The juxtaposition of the medieval stone arch with modern urban graffiti creates a stark contrast between the city s protected history and contemporary urban challenges. Tallinn, Estonia, October 16, 2025
 Cliffs of Enfield gorge in Robert H. Treman State Park. Ithaca, New York, November 2, 2005
 Stone Arch Bridge across Blackstone Canal in Blackstone River and Canal Heritage State Park. Uxbridge, Massachusetts, October 10, 2004
 Stone Arch Bridge across Blackstone Canal in Blackstone River and Canal Heritage State Park. Uxbridge, Massachusetts, October 30, 2004
 Stone Arch Bridge across Blackstone Canal in Blackstone River and Canal Heritage State Park. Uxbridge, Massachusetts, October 30, 2003
 Stone Arch Bridge across Blackstone Canal in Blackstone River and Canal Heritage State Park. Uxbridge, Massachusetts, October 30, 2003
 Tippecanoe River (after a drought) north from Lafayette, Indiana. September 18, 1999.
 Davis Ferry Bridge across Wabash River north from Lafayette. Indiana, September 11, 1999.
 Moyka River south from Summer Garden. Saint Petersburg, Russia, April 13, 1999.
 Hedge apples (osage orange) among first year garlic mustard leaves on a trail to Battle Ground. Indiana, November 26, 1999
 Canoe trip on Tippecanoe River with international students of Purdue University. Indiana, September 18, 1999.
 Tippecanoe River north from Lafayette, Indiana. Shallow places appeared after a drought. September 18, 1999.
 View of Longfellow Bridge across Charles River from Hancock Tower in Boston. Massachusetts, August 3, 1999.
 View of Back Bay, Charles River and Cambridge from Hancock Tower in Boston. Massachusetts, August 3, 1999.
 View of Charles River and downtown Boston from the top of Bunker Hill Monument. Massachusetts, July 31, 1999.
 Smol nyi Cathedral and monastery at a bend of Neva River in Saint Petersburg, Russia, April 21, 1999.
 Gulls on an embankment of Moyka River opposite to Summer Garden. Saint Petersburg, Russia, April 13, 1999.
 A meadow near Wabash River at Ross Hills Park 5 miles west from Lafayette. Indiana, October 30, 1999.
 A sphinx on Egypt Bridge across Fontanka River at Lermontovsky Prospect. Saint Petersburg, Russia, April 22, 1999.
 Moyka River and consulates of South-African Republic and France. Saint Petersburg, Russia, April 13, 1999.
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