Where is the largest telescope built?

The Gran Telescopio is 10.4m 409 inches, and was built by Spain and Meico

:P

The world's largest single-aperture telescope is the one located at the National

Astronomy and Ionosphere Center, near Arecibo in Puerto Rico.

It is a reflecting telescope, with an objective mirror that is 300 meters (1,000 feet)

in diameter. Its construction was completed in 1963, and it is used to study the

electromagnetic spectrum in the range of wavelengths from 3.00 centimeters to

1.00 meter.