Визит длился час.

In the past tense, Russian verbs agree with the subject in gender and number.

The subject here is визит, which is masculine singular, so the verb is длился.

Compare:

• встреча длилась час — встреча is feminine
• собрание длилось час — собрание is neuter
• переговоры длились час — plural

So длился matches визит.

The dictionary form is длиться, which means to last.

длился is the masculine singular past tense form of длиться.

So:

• длиться — to last
• длился — lasted, was lasting

The -ся ending originally comes from a reflexive form, but in many modern Russian verbs it is just part of the verb and does not need to be translated literally.

So длиться does not mean to last oneself. It simply means to last.

This is best learned as a whole verb:

• длиться — to last

Russian often expresses duration of time with no preposition at all.

So English for an hour is often just час in Russian.

Examples:

• Я ждал час. — I waited for an hour.
• Фильм длился два часа. — The film lasted two hours.
• Визит длился час. — The visit lasted an hour.

This is completely normal Russian structure.

It is accusative, used to express duration.

However, час is a masculine inanimate noun, and in the singular its accusative form looks exactly like the nominative form:

• nominative: час
• accusative: час

So the form does not change, even though the case does.

You can see the duration pattern more clearly with other words:

• неделя → неделю
  Визит длился неделю.
• минута → минуту
  Разговор длился минуту.

This is a very common point for learners.

длиться is normally an imperfective verb, but Russian often uses the imperfective past tense simply to state how long something lasted.

So Визит длился час is completely natural, even though the visit is over.

In Russian, imperfective past does not always mean the action was unfinished in real life. It can also present the event as a fact, especially with duration.

A very common pattern is:

• Фильм длился два часа.
• Урок длился сорок минут.
• Визит длился час.

No, not if you mean The visit lasted an hour.

быть means to be, and Визит был час is not the normal way to express duration.

For duration, Russian uses verbs like:

• длиться
• продолжаться

So the natural choices are:

• Визит длился час.
• Визит продолжался час.

Not always. In many contexts, it can mean simply an hour in a normal, approximate sense.

If you want to make it clearly exact, you can say:

• ровно час — exactly one hour

If you want to make it clearly approximate, you can say:

• примерно час — about an hour
• около часа — around an hour

So:

• Визит длился час. — neutral
• Визит длился ровно час. — exactly one hour
• Визит длился примерно час. — about an hour

Russian word order is flexible, but Визит длился час is the most neutral order.

This order is natural because it goes:

subject + verb + duration

Changing the order can shift emphasis, but some alternatives sound marked or unnatural in ordinary speech.

So for a basic statement, Визит длился час is the safest and most natural version.

The stress is:

визИт длИлся час

Word by word:

• визИт
• длИлся
• час

Stress is important in Russian because it is not always predictable from spelling.

Russian has no articles, so there is no separate word for a/an or the.

Whether визит means a visit or the visit depends on context.

So Russian simply says:

• Визит длился час.

And English may translate that as either:

• The visit lasted an hour
• A visit lasted an hour

depending on the situation.