Here are the top megaprojects with the biggest budget overruns.

2. THE CHANNEL
TUNNEL
Cost overrun: $21.1 billion (145%)
Delay: 1 year (20%)
Country: UK
Photo: Billy69150, Entrance to the tunnel near Coquelles, France
Wikipedia, CC BY-SA 4.0, https://creativecommons.org/licenses/by-sa/4.0/

3. THREE
GORGES DAM
Cost overrun: $16.1 billion (163%)
Delay: Ahead of schedule
Country: China
Photo: Rehman, Le Grand Portage, The Three Gorges Dam on the Yangtze River, China.
Wikipedia, CC BY 2.0, https://en.wikipedia.org/wiki/Three_Gorges_Dam#/media/File:ThreeGorgesDam-China2009.jpg

4. BOSTON’S
BIG DIG
Cost overrun: $13.4 billion (421%)
Delay: 9 years (128%)
Country: US

5. JUBILEE LINE
EXTENSION
Cost overrun: $4 billion (84%)
Delay: 2 years (50%)
Country: UK
Photo: Adrian Pingstone, The Jubilee Line platform of Westminster tube station, London, England.
Wikipedia, https://commons.wikimedia.org/wiki/File:Westminster.tube.station.jubilee.arp.jpg

6. DENVER
INTERNATIONAL
AIRPORT
Cost overrun: $3.1 billion (167%)
Delay: 16 months (100%)
Country: US

7. MONTREAL
OLYMPIC STADIUM
Cost overrun: $3 billion** (1990%)
Delay: On time
Country: Canada
** adjusted for inflation

8. BRAZIL WORLD
CUP STADIUMS
Cost overrun: $2.5 billion (227%)
Delay: On time
Country: Brazil
Photo: Brazilian Government, Maraca Stadium on June 2013
Wikipedia, CC BY 3.0 br, https://en.wikipedia.org/wiki/2014_FIFA_World_Cup_venues#/media/File:Maracana_Stadium_June_2013.jpg

9. WORLD TRADE CENTER
TRANSPORTATION HUB
Cost overrun: $2 billion (100%)
Delay: 4 years (140%)
Country: US

10. GREAT BELT
FIXED LINK
Cost overrun: $1.8 billion (54%)
Delay: On time
Country: Denmark

11. BUDAPEST
METRO LINE 4
Cost overrun: $1.6 billion over (353%)
Delay: 2 years (25%)
Country: Hungary