In world geography, which of the following cities is uniquely located so that one part lies in Asia and another part lies in Europe?

Introduction / Context:
The boundary between the continents of Europe and Asia is partly formed by seas, straits, and mountain ranges. Some cities are situated so close to this boundary that they span both continents. These transcontinental cities are often important cultural and commercial hubs, symbolising connections between different regions. This question asks which listed city has one part in Asia and another in Europe, making it a famous example of a city that straddles two continents.

Given Data / Assumptions:

• The focus is on a city whose territory extends across the conventional boundary between Europe and Asia.
• Options include Moscow, London, Istanbul, and Saint Petersburg.
• We assume knowledge of the general locations of these cities and the Europe Asia boundary.
• The correct answer should be a city that lies on both sides of a recognised continental dividing line.

Concept / Approach:
Istanbul in modern Turkey is widely known as a city that spans two continents. The Bosporus Strait runs through the city and is considered a boundary between Europe and Asia. The western side of Istanbul lies in Europe, while the eastern side lies in Asia, making it a transcontinental metropolis. Moscow and Saint Petersburg are both located entirely in the European part of Russia, even though the country as a whole extends deep into Asia. London is the capital of the United Kingdom and lies in Western Europe, far from the Asia Europe boundary. Therefore, only Istanbul fits the description of a city with parts in both continents.

Step-by-Step Solution:
Step 1: Identify which of the listed cities lies near the Bosporus Strait, a known boundary between Europe and Asia. Step 2: Recall that Istanbul is located on both sides of the Bosporus, with districts on the European and Asian shores. Step 3: Note that Moscow and Saint Petersburg, while belonging to a country that spans two continents, are themselves within the European section of Russia. Step 4: Recognise that London is entirely within Europe with no part in Asia. Step 5: Select Istanbul as the correct answer.

Verification / Alternative check:
Maps of Turkey and the region around the Bosporus clearly show Istanbul divided by the strait, with bridges and tunnels linking the European and Asian sides. Travel guides frequently describe visiting both continents within a single city by crossing from one side of Istanbul to the other. No similar description exists for London, Moscow, or Saint Petersburg, confirming that Istanbul alone meets the condition stated in the question.

Why Other Options Are Wrong:
Moscow is the capital of Russia and is located in the western, European part of the country; it does not cross into Asia. Saint Petersburg lies even further west, close to the Baltic Sea, and is also fully in Europe. London is situated in the United Kingdom on the island of Great Britain and is entirely in Europe. None of these cities straddle the Europe Asia boundary like Istanbul does, so they are not correct answers for this particular geographic feature.

Common Pitfalls:
Students sometimes assume that because Russia is a transcontinental country, its major cities such as Moscow must also be partly in Asia, which is not the case. Another mistake is confusing national geography with the location of specific cities. Remembering that Istanbul lies along the Bosporus Strait and is famously described as a bridge between Europe and Asia helps avoid these errors and leads quickly to the correct choice.

Final Answer:
The city that lies partly in Asia and partly in Europe is Istanbul.