Central Park, New York (1876)

Design: 843-acre public park with 26,000 trees, more than 40 bridges, as well as various lakes, paths, and meadows

Perks: Provided escape from hustle and bustle; trees annually produce 6.76 million pounds of oxygen

Drawbacks: Cost more than $10 million (approximately $169 million in 2010); displaced 1,600 poor people; created dark areas for criminals in 1980s

Building Time: 20 years

The Big Dig, Boston (2007)

Design: Highway and bridges that reroute the city’s Central Artery into a 3.5-mile tunnel

Perks: Decreased commuter travel time through downtown Boston by an average of 16 minutes; created 150 acres of parkland

Drawbacks: Cost $22 billion, more than eight times the original estimate; construction companies and subcontractors’ shoddy work led to a ceiling collapse, killing a driver

Building time: 16 years

Subway System, Tokyo (1927)

Design: Underground transportation for the city’s 2 million inhabitants on a 1.4-mile line between Ueno and Asakusa

Perks: Created first subway in East Asia; became one of the world’s most used systems, boasting 2.8 billion riders per year and 13 lines with 282 stations

Drawbacks: Provided target for 1995 sarin nerve-gas terrorist attack, which killed 12 and injured 5,500

Building time: 2 years

Catacombs, Paris (1788)

Design: Storage in quarries under the city of approximately six million people who had been previously buried in Parisian cemeteries

Perks: Cut down on noxious fumes; decreased deaths caused by infections near cemeteries; became tourist attraction

Drawbacks: Used by Royalists to hunt down Communards in 1871 and by Nazis as bunkers in World War II

Building Time: 3 years