Möchtest du auf dem Fensterplatz oder auf dem Gangplatz sitzen?

Möchtest du ... ? is a polite, softer way to say Do you want ... ? or Would you like ... ?

It comes from mögen and is the Konjunktiv II form often used for polite wishes or requests:

• du willst = you want
• du möchtest = you would like

So Möchtest du auf dem Fensterplatz oder auf dem Gangplatz sitzen? sounds more natural and polite than Willst du ... ? in many everyday situations.

Because this is a yes/no question in German.

In a normal statement, the verb would usually come second:

• Du möchtest auf dem Fensterplatz sitzen. = You would like to sit in the window seat.

But in a yes/no question, German normally puts the conjugated verb first:

• Möchtest du ... ? = Would you like ... ?

That is a very common pattern:

• Kommst du? = Are you coming?
• Hast du Zeit? = Do you have time?
• Möchtest du ... ? = Would you like ... ?

du is the informal singular word for you.

So this sentence is being said to:

• one person
• in an informal situation

If you wanted to say the same thing politely or formally, you would use Sie:

• Möchten Sie auf dem Fensterplatz oder auf dem Gangplatz sitzen?

That would be appropriate with a stranger, customer, passenger, etc.

Because Fensterplatz and Gangplatz are masculine nouns:

• der Fensterplatz = the window seat
• der Gangplatz = the aisle seat

After the preposition auf, German can use either:

• accusative for movement toward a destination
• dative for location

Here, the sentence is about being seated in a place rather than movement toward it, so German uses the dative:

• auf dem Fensterplatz
• auf dem Gangplatz

For masculine nouns, der becomes dem in the dative.

Yes, auf often means on, but prepositions do not always match English exactly.

In German, certain kinds of seats or places are commonly expressed with auf, even when English would say in:

• auf dem Fensterplatz = in the window seat
• auf dem Gangplatz = in the aisle seat

So this is something you should learn as an idiomatic German expression rather than translate word-for-word.

Because German often puts an infinitive verb at the end when it is used with a modal-like verb or another finite verb.

Here:

• möchtest is the conjugated verb
• sitzen is the infinitive

So the structure is:

• Möchtest du ... sitzen?

This is very common in German:

• Ich möchte schlafen. = I would like to sleep.
• Kannst du kommen? = Can you come?
• Willst du bleiben? = Do you want to stay?

The finite verb goes in the main verb position, and the infinitive goes to the end.

They are compound nouns:

• Fenster = window

• Platz = place/seat
  → Fensterplatz = window seat

• Gang = aisle
• Platz = place/seat
  → Gangplatz = aisle seat

German forms many nouns this way by combining smaller words into one longer noun.

oder means or.

It gives a choice between two options:

• auf dem Fensterplatz
• auf dem Gangplatz

So the whole sentence is asking which of the two the person prefers.

No. They are related, but they mean different things.

• sitzen = to be sitting / to sit
• sich setzen = to sit down

In this sentence, sitzen is used because the focus is on which seat you want to sit in.

Compare:

• Ich sitze auf dem Fensterplatz. = I am sitting in the window seat.
• Ich setze mich auf den Fensterplatz. = I sit down in the window seat / I take the window seat.

Notice that with sich setzen, German often uses the accusative because there is movement toward the seat:

• auf den Fensterplatz

With sitzen, it is a location, so:

• auf dem Fensterplatz

Because they are nouns, and in German all nouns are capitalized.

So:

• Fensterplatz
• Gangplatz

are capitalized, while words like:

• möchtest
• du
• auf
• oder
• sitzen

are not, unless they begin the sentence.

Yes, sometimes you can say am Fenster to mean by the window, but it is not exactly the same.

• am Fenster = by the window
• auf dem Fensterplatz = in the window seat

If you are specifically talking about seat selection on a train, plane, or bus, Fensterplatz and Gangplatz are more precise because they clearly refer to seat types.

So in this sentence, auf dem Fensterplatz oder auf dem Gangplatz is the most natural choice.