Column fluting, Biblioteca Nacional de España, Madrid. Photo © Emilio J. Rodríguez Posada, licensed under CC BY-SA 2.0. Source: Wikimedia Commons (originally posted to Flickr).

Bronze portrait of the emperor Hadrian, "Hadrian: An Emperor Cast in Bronze," Israel Museum, Jerusalem. Photo: Carole Raddato, licensed under CC BY-SA 2.0. Source: Wikimedia Commons.

The Trundholm Sun Chariot (Nordic Bronze Age, c. 1400 BC). Artifact is in the public domain. Reproduction photograph © National Museum of Denmark, licensed under CC BY-SA 3.0. Source: Wikimedia Commons.

Nicholas Roerich, Guests from Overseas (Заморские гости), 1901, oil on canvas. From the series "Beginnings of Russia. The Slavs." State Tretyakov Gallery, Moscow. Public domain. Source: Wikimedia Commons.

Washington Crossing the Delaware (1851) by Emanuel Leutze (1816–1868). Metropolitan Museum of Art, New York. Public domain. Source: Wikimedia Commons (Metropolitan Museum of Art).

Interior of the Pantheon, Rome (c. 1734) by Giovanni Paolo Panini (1691–1765). National Gallery of Art, Washington. Public domain. Source: Wikimedia Commons (National Gallery of Art, open access).

Sitges Train Station (1882) by Joan Roig i Soler (1852–1909). Oil on wood, Col·lecció Art de la Vila de Sitges. Digitized by the Google Art Project. Public domain, via Wikimedia Commons.

Sunrise, Yosemite Valley (c. 1870) by Albert Bierstadt (1830–1902). Amon Carter Museum of American Art, Fort Worth. Public domain. Source: Wikimedia Commons.

View of Warsaw from the Terrace of the Royal Castle (1773) by Bernardo Bellotto (1721–1780). National Museum in Warsaw. Public domain. Source: Wikimedia Commons (digitized via Google Art Project).

Dark Forest. Photograph released into the public domain under CC0 1.0. Source: rawpixel.

Meeting on a Bridge (1884) by Józef Brandt (1841–1915). Oil on canvas, National Museum in Kraków. Public domain (digital reproduction released under CC0 1.0). Source: Wikimedia Commons (National Museum in Kraków / Wikimedia Polska GLAM partnership).

Prayer in the Steppe (Our Lady of Pochaiv) (c. 1890) by Józef Brandt (1841–1915). National Museum in Warsaw. Public domain. Source: Wikimedia Commons.

Miners in the Sierras (1851–52) by Charles Christian Nahl (1818–1878) and Frederick August Wenderoth (1819–1884). Smithsonian American Art Museum. Public domain. Source: Wikimedia Commons (Smithsonian American Art Museum).

Madame Georges Charpentier and Her Children (1878) by Auguste Renoir (1841–1919). The Metropolitan Museum of Art, New York (Catharine Lorillard Wolfe Collection, Wolfe Fund, 1907). Public domain (CC0). Source: The Metropolitan Museum of Art.

Leaving the Opera in the Year 2000 (La Sortie de l'opéra en l'an 2000, c. 1882) by Albert Robida. Hand-colored lithograph. Public domain. Source: Wikimedia Commons (Library of Congress).

Allegory of Justice (1860), fresco in Santa Maria Maddalena, Castiglione del Lago. Photo © Wolfgang Sauber, licensed under CC BY-SA 4.0. Source: Wikimedia Commons.

Reconstructed Viking longhouse, Lofotr Viking Museum, Borg, Norway by Balou46. Licensed under CC BY-SA 4.0. Source:

View from Stalheim (1842) by Johan Christian Dahl (1788–1857). Artwork is in the public domain (artist died 1857). Reproduction image courtesy of the National Museum of Art, Architecture and Design, Oslo. Photo: Børre Høstland, Jacques Lathion / the National Museum. Licensed under CC BY 4.0. Source: Nasjonalmuseet.