For bibliophiles, an infinite tower of books is a nightmare disguised as a dream—a huge collection of literature that you can’t get at because pulling a book or two out will cause the collapse of the tower. But it does make for a wonderful sight.

A real-life iteration of this dream-nightmare is on display at the Prague Municipal Library. Artist Matej Kren’s “Idiom” is a long-term art installation where hundreds of books are stacked in a cylindrical tower. Mirrors placed at the bottom and the top give the exhibit the illusion of being infinite. A tear-shaped opening on one side of the tower allows visitors to peek in and experience what it would be like to drown in a book well.

Idiom was originally displayed at the Sao Paulo International Biennial in 1995, and found a permanent home in the entrance hall of the Czech library in 1998. This literary wormhole has become a local landmark in its own right, even featured on the cover of Science magazine in 2011.

Kren, who was born in Trencin, Slovakia, explores the theme of infinite knowledge offered by books in many of his works. “Gravity Mixer” is another book-themed installation, where Kren created a rotunda of books, and “Passage” in Bratislava is an endless looming wall of literature.