Left panel of Carleton Watkins' 3-part panorama of Portland, Or., 1867. Mount St. Helens is in the background.

Left panel of Carleton Watkins' 3-part panorama of Portland, Or., 1867. Mount St. Helens is in the background. Duplicate of Mammoth 402, on a different mount.

Left panel of Carleton Watkins' 3-part panorama of Portland, Or., 1867. Mount St. Helens is in the background. Duplicate of Mammoth 402, on a different mount.

Left panel of Carleton Watkins' 3-part panorama of Portland, Or., 1867. Mount St. Helens is in the background. Duplicate of Mammoth 402, on a different mount.

View of Cape Horn on the Washington side of the Columbia River Gorge, looking up the Columbia River. OHS Collection includes 1 duplicate of this mammoth plate on a different mount, with the alternate title, "Cape Horn Below the Cascades."

View of Cape Horn on the Washington side of the Columbia River Gorge. Taken from the east at John Stevenson’s property. Log cabin and fence in the foreground. OHS Collection includes 1 duplicate of this mammoth plate on a different mount, with the alternate title, "Cape Horn On Columbia River."

Distant view of Castle Rock, also known as Beacon Rock, across the Columbia River on the Washington side of the Columbia River Gorge. Taken from the McCrary farm in Oregon. OHS Collection includes 1 duplicate of this mammoth plate on a different mount.

View of Castle Rock, also known as Beacon Rock, on the Washington side of the Columbia River Gorge. OHS Collection includes 2 duplicates of this mammoth plate on different mounts.

View of the Middle Block House, also known as Fort Rains, on the Columbia River. OHS Collection includes 1 duplicate of this mammoth plate on a different mount.

View looking southwest down the Columbia River from the Middle Block House, also known as Fort Rains, in the Washington Territory. The Eagle Creek area is visible in the distance on the Oregon side of the river.

View of the former garrison at Fort Cascades, near the Cascades townsite on the Columbia River in Skamania County, Washington Territory, 1867. Castle Rock, also known as Beacon Rock, is visible in the distance.

A steam locomotive operated by the Oregon Steam and Navigation Company on railroad tracks in the Washington Territory of the Columbia River Gorge. Upper Block House, also known as Fort Lugenbeel, is on the left while a steamboat on the Columbia River is visible in the distance on the right.

View of the Upper Block House, also known as Fort Lugenbeel, on the Columbia River in the Columbia River Gorge. Other buildings and a railroad bridge are also visible. OHS Collection includes 2 duplicates of this mammoth plate on different mounts. One duplicate bears Watkins' signature on the back and has the alternate title, "Upper Blockhouse, Cascades."

View of the Columbia River Gorge from the Upper Block House, also known as Fort Lugenbeel, in the Washington Territory. View looks down the Columbia River. Railroad tracks border the river.

View of the Cascade Rapids on the Columbia River, taken from the Oregon side of the Columbia River Gorge. Upper Block House, also known as Fort Lugenbeel, is visible in the background on the left.