LONDON—A walk through the U.K.'s capital day and night during these Olympic Games reveals a world of centuries-old architecture blended with new construction on the very edge of modern engineering.

Olympic cities invest heavily to welcome the world's athletes. Designs, budgets, environmental impact reports and sustainability studies immediately followed the 2005 decision to award the 2012 Games to London; multiple projects already were in preplanning stages in anticipation of beating Paris in the final round for the bid. Some, like the sprawling Olympic Stadium and the Velodrome, were built specifically for competition. Others, such as the Shard skyscraper and the Emirates Air Line sky car were completed in time for the Games to show off the ambitions of British engineering.

But, this is England, a nation that has been around for more than a millennium. Before any construction can begin here, engineers must make certain that history won't be destroyed in the effort to build the future. To assess the massive Olympic Park site itself, archeologists dug 140 excavation pits. During the project they found a 19th-century fishing boat, human skeletons from the Iron Age, a roadway built in the 1700s and a hut from the Bronze Age.

»View a slide show of the design and engineering highlights of the London Olympics

LOCOG (London Organizing Committee of the Olympic and Paralympic Games) asked a historical preservation team to stand by to make sure these and any other archeological finds were preserved, removed and transported to a safe location for later public display at a site to be determined. Besides preserving history, construction plans also sought to protect the venue's environment. In keeping with the 21st-century Olympic ideal of environmental responsibility and sustainable design, the two million tons of earth used in forging and landscaping the site was cleansed of all detected pollutants.

A significant portion of the Olympic Park stands on what was once the Stratford rubbish tip. So, everything a garbage dump can leave behind had to be cleared from the soil used to shape the Park—including petroleum residue, biodegradable refuse, metal and rubber debris. And portions of the building materials removed from the site were transported and recycled for use in a pre-Olympics repair of the M25 motorway, the looping route that encompasses Central London.

According to London Media Center facts and figures, across its multiple venues in East London's Stratford, Olympic Park holds more than 200,000 temporary seats and 7,500 temporary lights hemmed in by 120 kilometers of fencing. Ten architects designed the park, which at 246 hectares is large enough to encompass 357 soccer fields, according to figures reported by the Queen Elizabeth Prize for Engineering. Some 30,000 construction professionals and engineers put in 700 million manpower hours combined to complete the project.

More than 130 kilometers of power cables installed 30 meters underground in two tunnels more than six kilometers long conduct electricity to the entire park. That feature alone cost $470 million. Another 480 kilometers of telecommunication cable crisscross the facilities—enough to "wrap around the London Eye [Ferris wheel] 1.3 million times," according to the Media Center. A lot of that cable flows to the center—a facility capable of handling 20,000 TV, print and online reporters at any given time.

Although the Park's tent city, media center and other elements will be dismantled when the Summer Olympics move on to Brazil, the park itself will be reconfigured as a residential community of 8,000 homes.

»View a slide show of the design and engineering highlights of the London Olympics