Simple past tense and past participle of landmark.(verb)
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Use "landmarked" in a sentence
"The sunlit restaurant, which has dishes from the museum's antique collection on its walls, faces the south facade of the American Natural History Museum, that is, the landmarked side."
"Bryan Derballa for The Wall Street Journal The condo, which was still under construction when the couple made the offer, is located in the Arches building at 401 Hicks St. The landmarked property was once the St. Peter's Roman Catholic Church, which was built in the 1850s."
"The owners of this two-bedroom condo in Cobble Hill, Brooklyn, were among the first to purchase a unit at the Arches, which was converted from a landmarked church."