Saudi Arabia's $500 billion megacity is in jeopardy after a Saudi journalist's death - here are the other multi-billion-dollar infrastructure projects set to go up

Though it goes by many names — "the forbidden mosque," "the holy mosque," "the sacred mosque" — the Great Mosque of Mecca is known universally as the largest mosque in the world.

With a history dating back to BCE, the structure has undergone numerous renovations, the latest of which was commissioned in 2007 by King Abdullahwik. Construction halted in 2015 when a crane collapsed into the mosque, killing more than 100 people.

With renovations back on, the mosque will soon be expanded to accommodate more than 2.5 million worshippers.

Saudi Arabia intends to build a high-tech city along the Red Sea coast that relies on renewable energy sources. At an estimated $25 billion, the project will create nearly 1 million housing units for around 6.5 million people by 2050. It also aims to provide 1 million jobs in fields like technology, health, and education.

The Riyadh Metro will soon become the main transportation system for Saudi Arabia's capital, introducing six new lines and 85 stations to the city. With 1.16 million passengers expected to rely on the metro within a few years of opening, the system could cut down on 250,000 car trips per day.

While the project expects to have a soft opening in 2019, officials said the metro will not be fully operational until 2021.

Jeddah Economic City is one of several ready-made cities being developed in Saudi Arabia.

At 56 million square feet, the city has enough room for a new transit system, office space, shops, beach resorts, luxury villas, and energy efficient homes. Its developer, Kingdom Holding Company, is owned by Prince Al-Waleed bin Talal, a member of the Saudi royal family.

Its first phase will center on the construction of the world's tallest tower, while phase two will develop the infrastructure. The entire project is set to open as early as 2026.

In 2016, the Saudi government partnered with Korean developer Hanwha Engineering & Construction to build 100,000 new homes near the Riyadh International Airport. The development, which is government-funded, is expected to be complete by 2020.

As of 2016, the Saudi government had 187 affordable housing projects in the works — an attempt to address the nation's considerable housing shortage.

Construction is well underway on the King Abdullah Financial District, a 17 million-square-foot development to the north of Riyadh. The project represents a key effort on behalf of Saudi Arabia to reduce its dependence on oil, which makes up around half of its economy.

While the new financial district is catered toward banks, law firms, and the nation's stock exchange, it will also be home to around 50,000 residents. Notable architectural features include a monorail, mosque, and network of skywalks connected by solar power.

The district is currently running behind schedule — despite being almost complete.

Read more: Saudi Arabia is building a $10 billion city on the sand — here's what it will look like

The newly renovated King Abdulaziz International Airport in Jeddah will officially open in January 2019. As a gateway for pilgrims traveling to the Two Holy Mosques in Mecca and Medina, the airport is designed to accommodate more than 80 million annual passengers.

In addition to a new terminal building, the renovations include a new five-star hotel, shopping centers, and public transportation system. The airport will also feature the world's tallest air traffic control tower, which will stand at nearly 450 feet.

Phase 5 of the King Abdullah Security Compounds includes the construction of 369 security facilities worth $8 billion. The development will include investigation and prosecution buildings, as well as security and immigration departments.

Saudi Arabia has taken on the trend of waterfront development, setting aside $5 billion for a new downtown area in Jeddah.

The project will include a mixture of residential, commercial, and office space, as well as a new hotel, amusement parks, and sports facilities. At around 54 million square feet, the development will also make room for around 12,000 new housing units.

A Dubai-based holding company is opening two new malls in Saudi Arabia, worth a reported total of $3.7 billion.

The first project, the Mall of Saudi, will become the largest shopping and entertainment complex in the nation. Its first phase of development — which includes a hotel, apartment building, and indoor ski slope — is set to be complete by 2022.

The second project, City Centre Ishbiliyah, will include 250 stores, a food court, and an entertainment complex.

Although the Abraj Kudai hotel was set to open in 2017, the building remains unfinished. With around 10,000 rooms and 70 restaurants, the hotel could soon become one of the largest in the world. Its amenities also include multiple helipads and a section set aside for the Saudi royal family.

The centerpiece of the Jeddah Economic City is the Jeddah Tower (formerly known as the Kingdom Tower), which will stretch 3,280 feet into the air. Once complete, the building will outstrip the Burj Khalifa for the title of world's tallest skyscraper.

Inside, visitors will find a Four Seasons hotel, office space, and luxury condos. The tower will also feature the world's highest observation deck, located on the 157th floor.

Read more: Saudi Arabia is building the world's tallest skyscraper — here's what it would look like