Yesterday officials from the European Southern Observatory announced where they plan to build the E-ELT, short for European Extremely Large Telescope.

If I ever hope to visit it someday, I'd better get in shape.

The chosen location is the summit of Cerro Armazones, a remote hilltop on the high plateau of central Chile. Topping out at 10,020 feet (3,060 m), it's not nearly the highest perch for a professional observatory. Mauna Kea's summit, for example, is 13,796 feet (4,207 m) above sea level.

But these days telescope location is more about "attitude" than altitude. Key factors include maximizing cloud-free nights, atmospheric stability ("seeing"), very low water-vapor content (for infrared observations), as well as costs of construction and operation. The ESO's site-selection team spent years assessing a short list of five peaks in Chile and on La Palma in the Canary Islands.

With a billion-euro price tag and a construction timetable projecting "first light" by 2018, the world's largest optical telescope will be a monster. Its primary's mosaic of 1,000 hexagonal mirrors will create an aperture 138 feet (42 meters) across. That's a huge engineering leap: four times the diameter of the largest single-aperture optical telescopes today. To put the optics in perspective, the E-ELT's secondary mirror will be bigger than the venerable Hale Telescope's 200-inch primary.

The ESO has prepared a very informative 28-page introduction to the E-ELT — but before you download that, have a look at this nifty series of interactive panoramas.

Now, where'd I put those jogging shoes?