ima tosyokan ni tuita tokoro desu.

Japanese often leaves out the subject when it is clear from context.

So instead of saying:

• 私は今図書館に着いたところです。

it is very natural to just say:

• 今図書館に着いたところです。

In conversation, the listener usually already knows who the speaker is talking about, so I, you, or we may be omitted.

Yes, 今 means now, but in this sentence it helps create the feeling of right now / just now.

Because the sentence also uses ～たところです, 今 strengthens the idea that the arrival happened very recently.

So the nuance is not just a general now, but more like:

• I’ve just arrived
• I arrived a moment ago

The particle に marks the destination or point of arrival with verbs like 着く.

So:

• 図書館に着く = to arrive at the library

This is similar to how に is used for a target or endpoint.

Compare:

• 学校に行く = go to school
• 駅に着く = arrive at the station
• 家に戻る = return home

With 着く, に is the normal particle for the place where someone arrives.

着いた is the plain past form of 着く.

Here, it appears before ところです, and that pattern requires the plain form:

• 辞書形 + ところです
• ている + ところです
• た形 + ところです

So:

• 着くところです = about to arrive
• 着いているところです = in the middle of arriving / arriving right now
• 着いたところです = just arrived

Even though the whole sentence ends politely with です, the verb before ところ stays in the plain form.

That is why 着きましたところです is not correct here.

In this sentence, ところです means something like at the point/stage of.

The pattern ～たところです means:

• have just done
• did something a moment ago

So:

• 着いたところです = have just arrived

This is a very common grammar pattern for talking about timing.

A useful comparison:

• 食べるところです = I’m about to eat
• 食べているところです = I’m eating right now
• 食べたところです = I just ate

So ところ here does not mean a physical place.

Not literally.

By itself, ところ can mean place, but in grammar patterns like ～ところです, it means more like:

• point
• stage
• moment

So in this sentence, 着いたところです is not the place where I arrived. It means:

• I am at the stage of having just arrived
• more naturally, I’ve just arrived

This is a very important difference, because learners often first memorize ところ = place, but it has a wider use in Japanese.

Japanese and English express this idea differently.

Japanese uses the past form 着いた because the arrival has already happened. Then ところです adds the idea that it happened just now.

So the literal logic is something like:

• I am at the point of having arrived

Natural English often uses the present perfect:

• I have just arrived

But Japanese does not need a special present perfect form here. The plain past form plus ところです does the job.

Both can mean that you arrived at the library now, but the nuance is a little different.

• 今図書館に着きました。
  = I arrived at the library just now / I’m at the library now.

• 今図書館に着いたところです。
  = I’ve just arrived at the library.

The second one emphasizes that the action happened very recently, almost at this exact moment. It focuses more on the timing.

So ～たところです often sounds a bit more specific and vivid when you want to stress just now.

This is because です is attached to the whole expression 着いたところ, not directly changing 着いた into polite form.

Structure:

• 着いた = arrived
• ところ = point/stage
• です = polite ending

So the sentence is polite overall, even though the verb before ところ is plain.

This is very common in Japanese grammar patterns.

For example:

• 食べるところです
• 読んでいるところです
• 終わったところです

All of these are polite because of the final です.

No. Normal Japanese writing would usually be:

• 今、図書館に着いたところです。

The spaces in your sentence are probably only there to help learners see the parts more clearly.

A natural written version would usually include:

• no spaces
• often a comma after 今
• a period at the end

So the standard form is:

• 今、図書館に着いたところです。

Yes, very naturally.

For example, if someone asks where you are, you could reply:

• 今、図書館に着いたところです。

This sounds like:

• I’ve just arrived at the library.

It is especially natural when you want to report your status right after arriving somewhere.

In casual speech, you might also say:

• 今、図書館に着いたところ。

That drops です and sounds more informal.