1. landmark - Noun
2. landmark - Verb
A mark to designate the boundary of land; any, mark or fixed object (as a marked tree, a stone, a ditch, or a heap of stones) by which the limits of a farm, a town, or other portion of territory may be known and preserved.
Any conspicuous object on land that serves as a guide; some prominent object, as a hill or steeple.
Source: Webster's dictionaryAs for the single market, the E.U.'s landmark achievement, there is no question that a euro zone breakup would severely disrupt its operation in the short run. Barry Eichengreen
The most advanced socialist thought in England is Raymond Williams' superbly intricate and persuasive work... Any English Marxism will have to measure itself against this landmark in our social thought. Perry Anderson
The de facto merger between Breitbart and the Trump Campaign represents a landmark achievement for the "Alt-Right." A fringe element has effectively taken over the Republican Party. Hillary Clinton
During his long tenure in the Supreme Court, he was a party to and author of a number of landmark judgments. Mohammad Hidayatullah
Whereas, our tenet ever was, and, indeed, it is almost the only landmark which now divides the federalists from the republicans, that Congress had not unlimited powers to provide for the general welfare, but were restrained to those specifically enumerated;... Thomas Jefferson
A landmark is very well placed between the fields of two brothers. French Proverb