Its roof is in ruins.

Moss covers the walls.

And sea water flows through every corner of it.

The last time people prayed here was in 2001, back when it was above ground.

Today, it's a warning sign.

It signals what could happen to Indonesia's  capital city if things don't change soon.

Because, even though Jakarta faces the same sea rising levels

as other coastal cities around the world,

that's not quite what we're looking at here.

Jakarta is sinking. And it's been sinking for decades.

These blue areas show just how much  the city has sunk since the 1970s.

The darker the area gets, the more it's dropped.

Here's how much it's descended today.

Most of the sinking happens here, in the north coast,

where Jakarta meets the Java Sea.

Here, the land is sinking by about 25 cm a year,  

destabilizing the area, damaging homes,

and upending people's lives, over and over again.

Many residents here are fishermen, who need  to live by the coast to make a living,

but, further inland, Jakarta's more than  10 million residents are also at risk.

A huge portion of the city, and the homes of millions, could be underwater by 2050.

Jakarta sits on a  swampy plain, on low coastal land.

It has 13 rivers that drain through it.

But the reason the city is sinking

is actually that most people here don't have enough water.

Most Jakartans lack access to clean, piped water.

Instead, they get their water  by digging wells like this one.

The pumps go deep into the ground to  extract the water stored in aquifers,  

underground layers of rock that hold groundwater.

The porous spaces of the rock are filled with it.

Multiply this by a few million,  and you have a problem.

Think of the rock as a soaked sponge:

the more water is extracted, the more it deflates,

causing the soil to compact and collapse, and the ground above it to sink.

Pumps alone shouldn't be able to do this.

While some layers of earth will never recover their water,

aquifers are usually refilled naturally when it rains.

But in Jakarta, that's becoming increasingly rare.

For decades, Jakarta has been developing at a fast pace,

and is now covered in concrete.

So the rainfall that would usually fill up the aquifers isn't being absorbed.

It's gotten so bad that in coastal areas prone to flooding,

like the fishing community Muara Baru,

people have built makeshift bridges  to move through their neighborhoods.

Combined with sea level rise,

it's also made floods during high tide and rainy seasons much more dangerous.

Like in 2007, when Jakarta experienced one of the worst floods

in its modern history.

A storm and high tide caused rivers and canals around the city to overflow,

killing 80 people.

Maksim has already lost his home to the sinking,

and now sleeps on his fishing boat.

And Nondho has had to rebuild his home several times.

Groundwater pumping is putting  Jakarta's survival at risk.

But to understand how it got into this situation to begin with,

you have to go back centuries.

In the 1600s, when European  powers were colonizing the world,  

the Dutch took over what was then  the port town of Jayakarta.

They razed it to the ground, and in its place, built Batavia:

a headquarters for their growing empire.

They began to rule over the Indonesian,  

Chinese, Indian, and Arab people  who had lived there for centuries,  

and built their new city in the Dutch style,

with narrow townhouses along a grid of canals.

The canals were used for trade, defense,  and to make Batavia feel like a Dutch city.  

But look at Batavia from above,

and you can see the city grid served a darker purpose, too.

If you look closely, you'll notice  that there aren't many bridges

between the two sides, or between the blocks.

This was by design. The Dutch were outnumbered.

So, in order to control the local population, they divided it.

It looked like this.

Pretty much every group was confined to their city quarter.

The Dutch ruled over the local population like this for over a century.

But that began to change in the mid-1700s.

Because the Dutch didn't properly maintain  the canals, they began to deteriorate,  

and sediment from earthquakes  blocked the flow of water.

The water in the canals turned  stagnant, and soon, deadly.

As disease spread through the canals,

the wealthier Dutch moved south of Batavia,

where they began to develop a new  colonial administrative center.

But, despite the death and disease, the Dutch continued to leave the canals untreated.

Instead, they began to use piped water.

In the 1870s, they developed the  first centralized water supply,  

with iron pipes to distribute water to homes.

The pipes provided clean drinking  water and indoor bathrooms.

But the pipes were concentrated in these  areas, where the Dutch had moved to.

The indigenous population was left in  informal settlements, called "kampongs,"

far from the piped water.

And this created a new kind of division in the city.

Native residents had to rely  on street vendors for water.

But most often, they were forced to get  their water from the neglected canals.

It took decades before pipes were  finally built in these communities.

And when they were, it would  only be a few public standpipes.

This continued through 1949.

After an armed conflict, the Dutch finally recognized Indonesia's independence, and left.

The legacy they left behind was a sprawling city,

built on marshland, and segregated by water access,

that, now, Jakartans had to deal with.

Over the next decades,  Jakarta's population skyrocketed.

More people required more housing, more stores, and more streets.

And the city expanded fast.

But its water infrastructure still  doesn't serve the majority of the city.

This chart shows how much of  Jakarta's population has piped water.

It was 12 percent in the 50s, and  is still under 50 percent today.

Many of the people without access to piped water

have no other choice but to keep pumping groundwater to survive.

And the city continues to sink.

The situation has gotten so bad,

the Indonesian government has talked  about moving the capital, from Jakarta,

to the neighboring island of Borneo.

But that won't help the millions  of people living in Jakarta.

To save the city, in 2014, the  government announced a project,  

in collaboration with a Dutch architecture firm,

to build and reinforce 120 km of seawalls,

to stop the water from flooding  the land as it sinks.

But so far, only these 10 kilometers have been reinforced.

Like this one in Muara Baru.

The problem is that, just like the rest  of Jakarta, the seawall is sinking.

The project also includes an ambitious $40 billion plan

to build a 38 km wall, shaped like a massive bird,

to protect the coast from flooding.

But this project could take  up to 30 years to complete.

And by then, Jakarta could have  lost most of its coastal land.

Jakarta will continues to sink until  groundwater stops being pumped.

And groundwater will continue to be pumped

until the government provides an alternative.

This has been done before. In the 1950s,

Tokyo managed to stop severe  sinking by providing piped water.

Taipei, Shanghai, Bangkok,  are other cities in the region  

that have managed to stop their cities from sinking.

But time is running out.

Jakarta has been free of Dutch rule for a little over 70 years now.

But the way the Dutch built their city, carved it up,

and restricted its water, plagues it to this day.

Jakarta is sinking into the sea.

And, until its government figures out how to provide clean, piped water for its citizens,

that will continue to be its reality.

For as long as it's still here.