IN MONTREAL, Canada, there is an old grain silo built in the 1950s to handle huge stockpiles that arrived by rail and left by sea.

Changes to world markets left the enormous structure obsolete and it closed down in 1996, leaving a concrete empty shell.

Inside, the hollow space has amazing acoustics. Any sound created inside is massively amplified and reverberates the length of the 45-metre high tube in unusual patterns.

This would have remained a local oddity if some bright spark didn't have the idea of installing digital sound equipment and hooking up the whole thing to the net.

The result is the Silophone (www.silophone.net), probably the world's biggest musical instrument. It qualifies as such because you can play it live over the web.

All you do is pick a sound from the long list provided on the site, or upload a sound file of your own straight from your hard disk.

As long as you have Real Player installed on your computer, you will hear your selected sound played back a few seconds later, deformed and distorted yet recognisable.

This kind of interactivity with a real object -- especially one so huge and unusual -- is a great application of simple web technologies.