The Grande Arche is a hollow concrete cube about 110 m on each side, standing at the western end of the historic axis of Paris in La Défense, and it weighs about 300,000 tonnes. Bouygues built it between 1985 and 1989. The competition design was by the Danish architect Johan Otto von Spreckelsen; Paul Andreu took the project forward after Spreckelsen resigned in July 1986, and Coyne et Bellier and Erik Reitzel are among the engineers named in published accounts.

The site was already occupied. The A14 motorway and the RER A run beneath it, and an extension of Metro line 1 was planned. The twelve concrete piers that carry the cube have bases about 30 m below ground-floor level, in ground reported as roughly 14 m of limestone over about 41 m of marl, and they had to land where those tunnels left room. Published accounts give both a structural and an architectural reason for the cube’s offset of about 6.3° from the axis; the structural one is that the piers could only go where there was space. The construction story sits higher up, in the roof.

≈110 m
Cube side
300,000 t
Total weight (approx.)
12
Foundation piers
4 × 110 m
Prestressed roof beams
≈2,500 t
Each beam (reported)
Phase 1 — The ground
Piers set between the tunnels
The twelve piers stand on bases about 30 m below ground-floor level. Settlement was monitored regularly and, according to the French account, always came out below the calculated estimates. The tunnels beneath the site decided where the piers could go, and the piers in turn set the position of the cube.
Phase 2 — The legs
Two legs climbing together
The two legs, which make up half of the cube’s floor area, were the repetitive part of the job. The reported cycle built the two floors at the same level of each leg together in four days. Four struts fitted with 2,000-tonne hydraulic jacks were placed at level 14 and stayed until the end of the works. The sources reviewed do not describe what they restrained.
Phase 3 — The roof
Four mega-beams cast in place
Each of the four prestressed beams is reported at 110 m long, 9.5 m high and about 2,500 t, with a clear span of 70 m. They were cast in place at the top of the structure from a steel centring carried on a very large rolling gantry, 90 m high and 70 m wide, each vertical member able to carry 1,000 t. Hydraulic-opening formwork in 10 m lengths let each beam be built in seven sections, with more than 100 m³ of concrete per section.
Phase 4 — The release
Stress, lower, move
Once a beam had been prestressed, the gantry was lowered by a few tens of centimetres on 1,000-tonne hydraulic jacks and then moved 21 m along. Prestressing shortened a 110 m beam by about 4 cm. More than 30,000 t of concrete went into the roof plateau about 100 m above ground, which French accounts describe as the feat of the project.
Four-phase schematic of the Grande Arche: twelve concrete piers set between the A14 and RER A tunnels with bases about 30 m down; two legs climbing together with four struts at level 14; a 110 m prestressed roof beam cast in seven sections on a 90 m high rolling gantry; and the gantry lowered by hydraulic jacks and moved 21 m to the next beam
The four phases behind the cube. Conceptual schematic, not to scale; section proportions, leg geometry and the function of the level-14 struts are not shown.
Sources: French Wikipedia, “Construction de la Grande Arche”, citing Chantiers de France no. 190 and Instantanés techniques no. 13 (1989); Structurae; Defense-92. Diagram: EE&HL Network, 2026.

The cube is remembered for its geometry. Its construction is better described by what had to be cast, stressed and released about 100 m in the air.

Casting prestressed beams in place from a rolling gantry, in sections, and then lowering and moving the supports after stressing is a sequence more usually met in bridge construction than in building work. That is an editorial reading; the sources reviewed do not draw the comparison themselves.

It also shows where construction-stage cost and risk can sit. The temporary works here were large, a gantry 90 m high with 1,000-tonne legs, yet none of it is visible in the finished cube. The record of the building is the geometry; the record of the build is in plant that left site before handover.

For how temporary supports are released once a structure can carry itself, see What Is a De-Propping Sequence? and Temporary Works & Erection Strategy. The same release question runs through the Beijing National Stadium and Singapore Sports Hub case studies.

Related case studies: Singapore Sports Hub · Beijing National Stadium · Gateway Arch · Eiffel Tower · Millau Viaduct

Core concepts: What is erection engineering? · What is heavy lift engineering?

Sources: French Wikipedia — “Construction de la Grande Arche” — roof beams, rolling gantry, formwork, level-14 struts, floor cycle, foundations and ground profile; it cites Chantiers de France no. 190 and Instantanés techniques no. 13 (1989); Structurae — dimensions, tunnels beneath the site, twelve foundation columns, inclination; Defense-92 — foundation stone 9 July 1985, inauguration July 1989, weight, the two reasons given for the rotation; Wikipedia — roles of Spreckelsen, Andreu and Reitzel; Bouygues as contractor; Batiactu — piers placed where space allowed. The beam dimensions and weights, gantry details and sequence figures above are as summarised in French Wikipedia’s construction article from period technical literature; the original articles could not be consulted and the figures should be read as reported. Other accounts describe the roof differently (for example as concrete traverses of 75 m) and quote different concrete volumes, so those are not used here. The sources reviewed do not state whether the legs were self-supporting before the roof beams connected them.

Frequently Asked Questions

Published accounts give two reasons. The structural one is that the foundation piers could only be placed where the motorway, RER and planned Metro line 1 tunnels left room. The architectural one, attributed to the architect, is that the offset emphasises the cube’s volume and echoes an existing misalignment in the axis. Sources quote the angle as about 6.3°.

According to French technical accounts summarised on French Wikipedia, each of the four prestressed beams, about 110 m long and 9.5 m high, was cast in place at the top of the structure from a steel centring on a rolling gantry 90 m high and 70 m wide. The formwork opened hydraulically and was used in 10 m lengths, so each beam was cast in seven sections. After prestressing, the gantry was lowered a few tens of centimetres and moved 21 m to the next beam.

It weighs about 300,000 tonnes and is carried by twelve concrete piers whose bases are about 30 m below ground-floor level. The ground below is reported as roughly 14 m of limestone over about 41 m of marl.

Bouygues built it between 1985 and 1989, from a competition-winning design by Johan Otto von Spreckelsen that was completed under Paul Andreu after Spreckelsen resigned in 1986. The foundation stone was laid on 9 July 1985 and the building was inaugurated in July 1989.