Located in Istanbul is the north-western Turkey and straddles the Bosporus Strait, which provides the only passage from the Black Sea to the Mediterranean via the Sea of Marmara.  The confluence of the Sea of Marmara, the Bosporus, and the Golden Horn provide both ideal defense against enemy attack and a natural toll-gate. You can explore some picturesque islands—Büyükada, Heybeliada, Burgazada, Kınalıada, and five smaller islands—are part of the city. Istanbul’s shoreline has grown beyond its natural limits. Large sections of Caddebostan sit on areas of landfill, increasing the total area of the city to 5,343 square kilometers (2,063 sq mi).

The threat of major earthquakes plays a large role in the city’s infrastructure development, with over 500,000 vulnerable buildings demolished and replaced since 2012. The nearby North Anatolian Fault is responsible for much earthquake activity, although it does not physically pass through the city itself, and a quake of at least magnitude 7 is more likely than not before 2030 and very likely in the 21st century. The fault caused the earthquakes in 1766 and 1894. 

The city has repeatedly upgraded its building codes, most recently in 2018,requiring retrofits for older buildings and higher engineering standards for new construction. Despite the myth that seven hills make up the city, there are, in fact, more than 50 hills within the city limits. Istanbul’s tallest hill, Aydos, is 537 meters (1,762 ft) high.

New York City is situated in the northeastern United States, in southeastern New York State, approximately halfway between Washington, D.C. and Boston. The location at the mouth of the Hudson River, which feeds into a naturally sheltered harbor and then into the Atlantic Ocean, has helped the city grow in significance as a trading port. Most of New York City is built on the three islands of Long Island, Manhattan, and Staten Island. The city’s land has been altered substantially by human intervention, with considerable land reclamation along the waterfronts since Dutch colonial times; reclamation is most prominent in Lower Manhattan, with developments such as Battery Park City in the 1970s and 1980s.  Some of the natural relief in topography has been evened out, especially in Manhattan.

The Hudson River flows through the Hudson Valley into New York Bay. Between New York City and Troy, New York, the river is an estuary.The Hudson River separates the city from the U.S. state of New Jersey. The East River—a tidal strait—flows from Long Island Sound and separates the Bronx and Manhattan from Long Island. The Harlem River, another tidal strait between the East and Hudson rivers, separates most of Manhattan from the Bronx. The Bronx River, which flows through the Bronx and Westchester County, is the only entirely freshwater river in the city.

The highest point in the city is Todt Hill on Staten Island, which, at 409.8 feet (124.9 m) above sea level, is the highest point on the eastern seaboard south of Maine. The summit of the ridge is mostly covered in woodlands as part of the Staten Island Greenbelt.

Milan is located in the north-western section of the Po Valley, it is about halfway between the river Po to the south and the foothills of the Alps with the great lakes (Lake Como, Lake Maggiore, Lake Lugano) to the north,  and to the east, you can see the spectacular Ticino river to the west and the Adda.  The highest point being at 122 m (400.26 ft) above sea level would be the city’s land is flat,.

A larger urban area, comprising parts of the provinces of Milan, Monza e Brianza, Como, Lecco and Varese is 1,891 square kilometres (730 sq mi) wide and has a population of 5,270,000 with a density of 2,783 inhabitants per square kilometre (7,210/sq mi), with the administrative commune covers an area of about 181 square kilometres (70 sq mi), with a population, in 2013, of 1,324,169 and a population density of 7,315 inhabitants per square kilometer (18,950/sq mi). The Metropolitan City of Milan covers 1,575 square kilometres (608 sq mi) and in 2015 had a population estimated at 3,196,825, with a resulting density of 2,029 inhabitants per square kilometre (5,260/sq mi).

The city have expanded the suburbs of mainly to the north, swallowing up many communi along the roads towards Varese, Como, Lecco and Bergamo. The concentric layout of the city center reflects the Navigli, an ancient system of navigable and interconnected canals, now mostly covered.

As a German state government, it is responsible for public education, correctional institutions and public safety, as a municipality, it is additionally responsible for libraries, recreational facilities, sanitation, water supply and welfare services. The city of Hamburg is one of 16 German states, therefore the Mayor of Hamburg’s office corresponds more to the role of a minister-president than to the one of a city mayor.

Since 1897, the seat of the government has been Hamburg City Hall (Hamburg Rathaus), with the office of the mayor, the meeting room for the Senate and the floor for the Hamburg Parliament. From 2001 until 2010, the mayor of Hamburg was Ole von Beust, who governed in Germany’s first statewide “black-green” coalition, consisting of the conservative CDU Hamburg and the alternative GAL, which are Hamburg’s regional wing of the Alliance 90/The Greens party. Von Beust was briefly succeeded by Christoph Ahlhaus in 2010, but the coalition broke apart on 28 November 2010. On 7 March 2011 Olaf Scholz (SPD) became mayor. After the 2015 election the SPD and the Alliance 90/The Greens formed a coalition.

The city center is around the Binnenalster (“Inner Alster”) and Außenalster (“Outer Alster”), both formed by damming the River Alster to create lakes. Sheltered with natural harbour on the southern fanning-out of the Jutland Peninsula, between Continental Europe to the south and Scandinavia to the north, with the North Sea to the west and the Baltic Sea to the northeast, that is Hamburg. It is on the River Elbe at its confluence with the Alster and Bille.