2 World Trade Center (1971–2001)

Two World Trade Center (South Tower)

Company type	Office skyscraper
Industry	Commercial real estate
Founded	1973
Defunct	2001-09-11
Fate	Destroyed in the September 11 attacks
Headquarters	New York City , United States
Key people	Minoru Yamasaki (architect), Emery Roth & Sons (associate architects)
Products	Office space, observation decks
Parent	Port Authority of New York and New Jersey (original owner)

The original Two World Trade Center—also referred to as the South Tower, Tower 2, or 2 WTC—was one of the Twin Towers within the original World Trade Center Complex located in New York City. Completed and inaugurated in 1973, it reached a rooftop height of . Unlike its counterpart, the North Tower, it did not feature a television antenna. The building housed the well-known "Top of the World Trade Center Observatories" on its 107th floor, along with an outdoor observation deck on the roof that included an unused helipad. Its official mailing address was 2 World Trade Center, situated within the complex's distinctive ZIP code.

The South Tower was destroyed during the events of the September 11 attacks. At about 9:03 a.m., seventeen minutes after the North Tower was impacted, it was struck by United Airlines Flight 175. Although it was the second tower to be hit, it collapsed first at 9:59 a.m., following 56 minutes of intense fire. Of the total 2,977 casualties from the attacks, approximately 1,000 were inside or near this tower.

Current proposals for the new 2 World Trade Center, which remain paused, feature a stepped façade design and exclude an observation deck or mechanical floors. The southern pool at the National September 11 Memorial & Museum marks where the South Tower once stood.

Development

In 1961, the Port Authority of New York and New Jersey agreed to construct the World Trade Center on the former site of the Hudson Terminal in Lower Manhattan, New York City. On , 1962, Minoru Yamasaki was appointed lead architect, with Emery Roth & Sons serving as associate architects. Yamasaki initially envisioned twin towers with 80 stories each; however, to fulfill the Port Authority's requirement for of office space, both towers were redesigned to rise to 110 stories. This design, revealed on , 1964, featured a square footprint measuring approximately on each side.

Property acquisition at the site began in March 1965 under the Port Authority’s direction. Demolition commenced on , 1966, followed by groundbreaking later that year on . In January 1967, contracts valued at $74 million were awarded to steel fabricators. Construction of the South Tower started by ; it reached its topping out milestone on , 1971. Tenant occupancy began in , culminating with an official opening ceremony on , 1973.

Operation

In response to a significant fire in the North Tower in 1975, the Port Authority announced a $45 million initiative in 1981 to install sprinkler systems throughout the World Trade Center complex.

On February 26, 1993, a Ryder truck laden with approximately 1,500 pounds of explosives—planted by Ramzi Yousef—detonated in the underground garage of the North Tower. The attackers intended to weaken the North Tower’s structure sufficiently to cause it to collapse onto the South Tower, thereby bringing down both buildings. The bombing resulted in six fatalities and injured over a thousand individuals.

In February 2001, control of the entire World Trade Center complex was leased by the Port Authority to Vornado Realty Trust. However, due to last-minute stipulations demanded by Vornado, Silverstein Properties ultimately signed the lease agreement on July 24, 2001.

September 11 attacks

At 9:03 a.m. EDT on September 11, 2001, five hijackers flew United Airlines Flight 175 into the South Tower’s southern facade. This impact, along with two other buildings in the World Trade Center complex including 2 WTC, resulted in their collapse caused by fire-compromised structural elements. The towers’ relatively lightweight construction allowed jet fuel to penetrate deeply, igniting extensive fires throughout. Although the jet fuel burned out within minutes, the contents inside the buildings sustained fires for more than an hour.

If the structures had been built with heavier high-rise construction methods, it is likely that debris and fuel would have remained largely external or peripheral, which might have prevented failure at critical core points and extended the towers’ structural integrity. The intense heat weakened steel columns and caused floors to deform downward, pulling perimeter columns inward and compromising support. The South Tower ultimately collapsed at 9:59 a.m., approximately 56 minutes after impact and subsequent fuel ignition.

Architecture

The principal architect behind the towers was Minoru Yamasaki, with Emery Roth & Sons serving as associate architects. Structural engineers adhered to preliminary versions of New York City's 1968 building code, integrating innovative design approaches. Employing a tube-frame structural system, the Twin Towers utilized about 40% less steel than traditional buildings of similar size. Drawing inspiration from Le Corbusier and Yamasaki’s gothic modernist influences, the design also incorporated motifs from Islamic architecture, reflecting his previous work on Saudi Arabia's Dhahran International Airport.

Finished in 1973, the South Tower ranked as the world’s second tallest structure at , just slightly shorter than its counterpart, the North Tower. Its rooftop observation deck was situated at , complemented by an indoor observation area at . Each tower rose above in height and covered roughly of the entire site’s land area.

Facade

The facades of the Twin Towers were composed of high-strength steel perimeter columns that served as load-bearing elements arranged as Vierendeel trusses. Despite their lightweight nature, these densely spaced columns created a robust and rigid exterior wall. Every face contained 59 columns spaced at intervals of 3 ft 4 in, with perimeter walls measuring per side and featuring beveled corners. The facade was constructed from prefabricated modular sections connected via spandrel plates. From the seventh floor down to the foundation, column spacing increased to accommodate doorways. All columns were firmly anchored into bedrock located between 65 and 85 feet (20–26 m) below ground level.

Structural features

The towers’ cores housed elevator shafts, mechanical rooms, restrooms, and three stairwells within a rectangular footprint measuring 87 by 135 feet (27 by 41 m). This core structure contained 47 steel columns extending continuously from bedrock to rooftop and supported approximately half of each building’s weight. Elevators and most stairwells were concentrated within this central core. Prefabricated floor trusses spanned the open space between core and perimeter columns, creating large column-free floor areas.

From the 107th floor upward, hat trusses (also known as "outrigger trusses") were installed to provide support for tall communication antennas; however, only the North Tower featured an antenna installation. The framed-tube structural concept combined a steel core with perimeter columns coated in sprayed-on fire-resistant materials, resulting in a relatively lightweight frame engineered to flex under wind forces. Engineer Leslie Robertson incorporated considerations for potential jetliner collisions during design. The National Institute of Standards and Technology (NIST) found some indication that aircraft impacts at speeds up to had been analyzed, though documentation was sparse.

Fireproofing involved sprayed fire-resistant materials (SFRMs), gypsum board, and vermiculite coatings. Following a fire in 1975, additional fireproofing was applied; nevertheless, inspections after the 1993 bombing revealed several deficiencies. While New York City building codes from 1968 did not mandate sprinkler systems for high-rises except in underground areas, by 2001 the entire World Trade Center complex had been retrofitted with sprinkler systems.

Tenants

Note: Floors highlighted in  red  were located within the impact area of United Airlines Flight 175 during the September 11 attacks; floors above are indicated in  dark gray .

Floor #	Occupants	Industry
R	Outdoor Observatory (Top of the world)	Tourism
109	Mechanical floor
108	Mechanical floor
107	Showtime Pictures, Top of the World Trade Center Observatories (Indoor Observatory), Sbarro Street Station, Nathan's Famous Hot Dogs, Manhattan Magic, Kodak	Business services, Tourism, Food, Entertainment
106	Atlantic Bank of New York	Banks/Financial
105	AON Corporation	Insurance
104	AON Corporation, Sandler O'Neill and Partners	Insurance, Investment
103	AON Corporation	Insurance
102	AON Corporation	Insurance
101	AON Corporation	Insurance
100	AON Corporation	Insurance
99	AON Corporation	Insurance
98	AON Corporation	Insurance
97	Fiduciary Trust Company International	Banks/Financial
96	Fiduciary Trust Company International	Banks/Financial
95	Fiduciary Trust Company International	Banks/Financial
94	Fiduciary Trust Company International	Banks/Financial
93	AON Corporation, Regus Business Centers	Insurance, Co-working
92	AON Corporation	Insurance
91	Gibbs & Hill, Raytheon Company, Washington Group International	Engineering, Manufacturing
90	Fiduciary Trust Company International	Banks/Financial
89	Keefe, Bruyette & Woods	Investment
88	Keefe, Bruyette & Woods	Investment
87	New York State Department of Taxation and Finance, Corporation Service Company	Government, Financial
86	New York State Department of Taxation and Finance	Government
85	Harris Beach & Wilcox	Attorneys
84	Euro Brokers	Financial Services
83	IQ Financial Systems, Chuo Mitsui Trust & Banking	Financial Services
82	Fuji Bank	Banks/Financial
81 to 79	Fuji Bank	Banks/Financial
78	Skylobby, First Commercial Bank, Baseline Financial Services	Banks/Financial, Financial Services
77	Baseline Financial Services	Financial Services
76 to 75	Mechanical floors
74 to 63	Morgan Stanley	Investment Banking and Services
62	Morgan Stanley, Demeter Management Corporation	Investment, Not available
61 to 59	Morgan Stanley	Investment Banking and Services
58	Bridge Information Systems	Financial Information Provider
57	Hold Brothers	Financial Services
56	Morgan Stanley	Investment Banking and Services
55 to 50	Guy Carpenter, Garban Intercapital, Harlows	Reinsurance, Investment, Not available
49	Guy Carpenter, Seabury & Smith	Reinsurance, Insurance
48	Fireman's Fund Insurance Company, Guy Carpenter	Insurance, Reinsurance
47 to 46	Guy Carpenter, Morgan Stanley	Reinsurance, Investment
45 to 43	Morgan Stanley	Investment Banking and Services
42 to 41	Mechanical floors
40 to 38	Sitailong International USA, Thacher Proffitt & Wood, LLP	Not available, Attorneys
37	'—'
36 to35	'Frenkel and Company'	Insurance
34 to31	'OppenheimerFunds', 'Commerzbank Capital Markets' (32nd floor)	Investment, Financial Services
30 to28	'New York Stock Exchange', 'Hartford Steam Boiler', 'Weatherly Securities Corp.', 'Big A Travel Agency', 'Law Office Of Joseph Bellard', 'Hua Nan Commercial Bank Ltd.'	Financial, Insurance, Transportation, Law Firms, Financial Institutions
27	'—'
26 to25	'Sun Microsystems'	Computer services
24 to23	'Allstate Insurance Company', 'China Chamber of Commerce', 'Globe Tour and Travel', 'SCOR U.S. Corporation', 'Sinolion', 'TD Ameritrade', 'Unistrat Corporation of America'	Insurance, Organizations, Travel, Investment, Consultants
22 to21	'Antal International', 'Mancini Duffy', 'NYS Retirement System', 'Adecco SA', 'Career Engine', 'Matthews & Wright Inc.', 'Taiwan Sugar Corporation'	Not available or Employment agency and Architecture firms
20 to19	'Thacher Proffitt & Wood, LLP', 'New York Shipping Association', 'Waterfront Commission of New York Harbor'	Attorneys, Transportation
18 to17	'AbraCadabra Digital Printing', 'Alliance Consulting Group', 'Weiland International Inc.', 'New York Institute of Finance'	Business services, Banks/Financial
16 to15	'National Development and Research Institute', 'Candia Shipping', 'Orient International' (merged with Yuanta Securities), 'CINDE Costa Rican Investment Board', 'DigiOrbit Corporation', 'Millennium Management Resources Inc.', 'Optech Systems Inc.', 'Stallion Commerce Corporation', 'TD Ameritrade'	Research, Shipping, Investment Banking/Financial
14 to13	'Charna Chemicals', 'Paging Network of New York', 'Patinka International (USA)', 'Union Bank of California', 'Verizon Communications'	Manufacturing, Telecommunication, Business services, Banking
12 to9	'Verizon Communications' with some shipping companies on the lower floors	Telecommunication and Shipping
8 to7	'Mechanical floors'
'—'
'TKTS'	Ticket booth
'Nichols Foundation', 'Colortek Kodak Imaging Center'	Government/Schools, Business services
'The Mall at the World Trade Center'	Retail
'Xerox Document Company', 'Anthem (company)', NY Chamber of Commerce	Manufacturing, Insurance, Government
'Continental Insurance Company'	Insurance

Note: Even though Atlantic Bank of New York left in July of 2001, they remained responsible for rent payments through September.

External links

• Building: 2 World Trade Center - South Tower CNN