Gedung ini berumur satu abad.

Gedung usually means a building, especially a fairly large or substantial one such as an office building, school building, or public building.

It is not usually used for a house. For house, Indonesian normally uses rumah.

A few useful comparisons:

• gedung = building, especially a large/important one
• bangunan = structure/building in a more general sense
• rumah = house/home

So Gedung ini means this building.

In Indonesian, demonstratives like ini (this) and itu (that) usually come after the noun.

So:

• gedung ini = this building
• gedung itu = that building

If you say ini gedung, that usually works differently in the sentence and can sound more like this is a building or be used in special contexts, not the normal way to say this building.

So for a noun phrase, the standard pattern is:

• noun + ini/itu

Berumur means to have an age or to be ... years old / ... old.

In this sentence:

• Gedung ini berumur satu abad
  = This building is one century old

Literally, it is something like:

• This building has an age of one century

Indonesian often uses this kind of structure where English uses to be old.

The prefix ber- often forms an intransitive verb and can give the idea of having, wearing, using, or possessing something, depending on the word.

Here:

• umur = age
• berumur = to have an age / to be aged

So berumur satu abad literally suggests having an age of one century.

You do not need to translate ber- separately every time, but it helps to recognize that it changes the noun umur into a verb-like form.

Indonesian often does not use a verb like is/am/are in simple present statements.

So instead of saying something equivalent to This building is one century old with a separate word for is, Indonesian simply says:

• Gedung ini berumur satu abad

This is completely normal. Indonesian frequently leaves out a copula in sentences where English requires to be.

It can be used for both living things and things like buildings, objects, institutions, and so on.

For example:

• Anak itu berumur lima tahun = That child is five years old
• Gedung ini berumur satu abad = This building is one century old

So using berumur for a building is natural.

Satu abad means one century.

You could also say:

• seratus tahun = one hundred years

Both are correct in meaning here:

• Gedung ini berumur satu abad
• Gedung ini berumur seratus tahun

The version with abad sounds a bit more compact and sometimes a little more formal or literary, while seratus tahun is very straightforward and common.

Yes, seabad can also mean one century.

So you may see:

• berumur satu abad
• berumur seabad

Both are understandable. Satu abad may feel a bit more explicit to learners, while seabad is a more compact form.

You can also say berusia, and it is very common.

For example:

• Gedung ini berumur satu abad
• Gedung ini berusia satu abad

Both mean essentially the same thing: This building is one century old.

In many contexts, berusia can sound a little more formal or neutral, but both are good.

Yes, you could say Gedung ini tua, which means This building is old.

However, the meaning is less specific.

Compare:

• Gedung ini tua = This building is old
• Gedung ini berumur satu abad = This building is one century old

So tua gives a general description, while berumur satu abad gives the exact age.

Satu is the basic number one.

In satu abad, it simply means one century.

Sebuah is a classifier-based form often used with countable nouns, especially objects:

• sebuah gedung = a building / one building

But time spans like abad are normally expressed directly with numbers:

• satu abad
• dua abad
• tiga tahun

So satu abad is the natural choice here.

The structure is:

• Gedung ini = subject noun phrase (this building)
• berumur satu abad = predicate (is one century old / has an age of one century)

So the overall pattern is:

• Subject + predicate

More literally:

• [This building] [has an age of one century]

That is why the sentence feels simple and direct in Indonesian.