Massive construction projects are very complicated - and very expensive.
It is vital the finished building is safe for the people who use it.
Corner-cutting can often lead to disaster, and attempts to save money or maximize profit over safety often lead to huge fines and even prison for those involved.
One horrific incident happened in South Korea in the 1990s, which led to prison sentences for board members who chose to make money over introducing safety measures.
South Korea had seen a boom in construction in the run-up to the Seoul Olympics in 1988, with several massive contracts handed out for enormous building projects.
One project was the Sampoong Department Store.
The project started life as an apartment block in 1987 but was taken over by the Sampoong Group.
The head of its construction division, Lee Joon, decided it should become a shopping mall and ordered changes to concrete support columns.
This involved cutting away several support columns to put in escalators and adding a fifth floor, which would've been an ice rink but ended up being a food court.
The building company in charge withdrew due to safety concerns.
Lee Joon then brought in his own company to finish the work to create what became the Sampoong Department Store, which opened in 1990.
To maximize the floor space in the store - to make more money - Lee Joon ordered the size of the floor columns to be reduced to 60cm (24ins) thick.
The minimum for the building to stand safely was 80cm (31ins).
The columns were too far apart, meaning each one was taking more weight than it should.
Warning signs
Warning signs started to appear in April 1995 when cracks began to show in the ceiling of the fifth floor.
Lee Joon's response was to move merchandise and stores from the top floor to the basement.
On June 29 of the same year, more cracks appeared, which led to parts of the top floor being shut off.
However, managers failed to close the building or issue evacuation orders.
The store was exceptionally busy at the time, and management decided they did not want to lose a day's revenue.
Inspectors were quickly able to tell the building was at risk of collapse.
Then, five hours before the collapse, a series of loud bangs were heard from the top floors as vibrations from air conditioning units caused the cracks to widen.
The units were subsequently turned off, but the cracks had increased considerably.
Disaster
It became clear the building would collapse, and the board held an emergency meeting.
Despite the looming disaster, Lee Hoon still refused to evacuate the building due to his fears of losing cash.
The executives made sure they were safe before the collapse.
It was later revealed Jee Joon didn't even tell his daughter-in-law, who worked in the building.
She ended up being trapped in the rubble and was rescued days later.
At around 5pm, the ceiling on the fifth floor began to sink.
During the trial, Lee Joon continued to cause controversy by saying the collapse harmed customers and inflicted significant financial damage to his company.
In December 1995, he was found guilty of criminal negligence and received a prison sentence of 10-and-a-half years.
He died a month after his release from prison, aged 81.
His son and the store's CEO, Lee Han-sang, was jailed for seven years for accidental homicide and corruption.
He was released in 2002 and spent time working as an evangelist in Mongolia.
City officials Lee Chung-Woo, and Hwang Chol-Min were also jailed for three years and 10 years for accepting bribes from Lee Joon.
Other officials, store executives, and staff from the company who built the shopping center were also jailed.
The former shopping center is now luxury apartments, which opened in 2004.
