The Brandenburg Gate (German: Brandenburger Tor) is an 18th-century neoclassical triumphal arch in Berlin, and one of the best-known landmarks of Germany. It is built on the site of a former city gate that marked the start of the road from Berlin to the town of Brandenburg an der Havel. It is located in the western part of the city centre of Berlin within Mitte, at the junction of Unter den Linden and Ebertstraße, immediately west of the Pariser Platz. One block to the north stands the Reichstag building that houses the German parliament (Bundestag). The gate is the monumental entry to Unter den Linden, the renowned boulevard of linden trees, which led directly to the royal City Palace of the Prussian monarchs.

Having suffered considerable damage in World War II, the Brandenburg Gate was fully restored from 2000 to 2002 by the Stiftung Denkmalschutz Berlin (Berlin Monument Conservation Foundation).

Source: https://en.wikipedia.org/wiki/Brandenburg_Gate

The Eiffel Tower is a wrought iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower. Constructed in 1889 as the entrance to the 1889 World's Fair, it was initially criticized by some of France's leading artists and intellectuals for its design, but has become a global cultural icon of France and one of the most recognisable structures in the world.The tower is the tallest structure in Paris and the most-visited paid monument in the world: 6.98 million people ascended it in 2011. The tower received its 250 millionth visitor in 2010.

The tower is 324 metres (1,063 ft) tall, about the same height as an 81-storey building. Its base is square, 125 metres (410 ft) on a side. During its construction, the Eiffel Tower surpassed the Washington Monument to become the tallest man-made structure in the world, a title it held for 41 years until the Chrysler Building in New York City was built in 1930. Not including broadcast aerials, it is the second-tallest structure in France, after the Millau Viaduct.
Source: https://en.wikipedia.org/wiki/Eiffel_Tower

Denver is the capital and most populous municipality of the U.S. state of Colorado. As of 2015, Denver is also the most populous county in Colorado. Denver is located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains. The Denver downtown district is located immediately east of the confluence of Cherry Creek with the South Platte River, approximately 12 mi (19 km) east of the foothills of the Rocky Mountains.

Denver is nicknamed the Mile-High City because its official elevation is exactly one mile (5,280 ft or 1,610 m) above sea level, making it one of the highest major cities in the United States. The 105th meridian west of Greenwich, the longitudinal reference for the Mountain Time Zone, passes directly through Denver Union Station.

Source: https://en.wikipedia.org/wiki/Denver

The City of New York, often called New York City or simply New York, is the most populous city in the United States. Located at the southern tip of the State of New York, the city is the center of the New York metropolitan area, one of the most populous urban agglomerations in the world. A global power city, New York City exerts a significant impact upon commerce, finance, media, art, fashion, research, technology, education, and entertainment, its fast pace defining the term New York minute.

Situated on one of the world's largest natural harbors, New York City consists of five boroughs, each of which is a separate county of New York State. The five boroughs – Brooklyn, Queens, Manhattan, The Bronx, and Staten Island – were consolidated into a single city in 1898. With a census-estimated 2015 population of 8,550,405 distributed over a land area of just 305 square miles (790 km2), New York is the most densely populated major city in the United States.
Source: https://en.wikipedia.org/wiki/New_York_City

Portland is the largest city in the U.S. state of Oregon and the seat of Multnomah County. It is located in the Willamette Valley region of the Pacific Northwest, at the confluence of the Willamette and Columbia rivers. Approximately 2,348,247 people live in the Portland metropolitan statistical area (MSA), the 24th most populous MSA in the United States.

Named after the city on the coast of Maine (which was named after the English Isle of Portland), the Oregon settlement began to be populated in the 1830s near the end of the Oregon Trail. Its water access provided convenient transportation of goods, and the timber industry was a major force in the city's early economy. At the turn of the 20th century, the city had developed a reputation as one of the most dangerous port cities in the world, a hub for organized crime and racketeering. Beginning in the 1960s, Portland became noted for its growing liberal political values, and the city has earned a reputation as a bastion of counterculture, a view which has proceeded into the 21st century.
Source: https://en.wikipedia.org/wiki/Portland,_Oregon