Idiom – Infinity Book Tower Installation – Everything you need to know
Directly opposite the main entrance doors of the Municipal Library on Mariánské Square in the middle of the Old Town is another one of my favourite hidden gems in Prague known as the “Endless Well.”
It’s a large tower of books stacked from ground to the ceiling, with two mirrors facing each other inside. This creates the illusion of infinite space, when you look inside.
I often do my research at the Main Library and I also write my View from Prague blog there, so I’ve been walking past the book tower for the last few years countless times.
It’s nice to see people enjoying the installation idea and smiling as they look into the book tunnel. It’s fun art, but I love that the installation has a deeper meaning at the same time.
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My favourite reasons for visiting the Idiom – the Infinity Book Tower
The Idiom sculpture is meant to symbolize the infinity of knowledge. You can experience this feeling by looking inside through the front of the sculpture and when you look up or down, all you will see are the book.
This is also why people are waiting there, because it’s not just enough to take a quick picture with the book tower, you really need to look at the installation from the inside.
There are two mirrors—one at the top and one at the bottom, which creates the impression of infinity. It’s so effective, that if you suffer with vertigo or seasickness, you might need to be a bit careful because you can easily feel queasy.
What is The Idiom – Infinity Book Tower ?
Idiom is a column made of 8,000 books, which has been installed in the Prague Central Library since 1998. The creator of Idiom, also known as the “Column of Knowledge, book tunnel, book tower or endless well,” is Slovak artist Matej Krén. Over its 26-year life, the book Idiom has become more and more popular and it attracts not only tourists but also Prague residents.
Some of these books have been donated by the library and some were rescued from being pulped and turned back to paper.
The installation has even been featured in the Lonely Planet guide and on the cover of the scientific journal Science. It’s also a bit of a Tik Tok phenomenon as it’s being constantly shared as one of the top things to see in Prague.
My favourite fun fact about the Idiom sculpture
The installation had to be rebuilt several times over the past 26 years. This is not just because of the large visiting numbers and people constantly walking around the installation.
The artwork also needs regular maintenance because the Prague metro runs beneath the library and the ground moves a bit every time the train runs through.
What you should know before you visit
The obvious rule is not to touch the sculpture and try to lean in as carefully as you can. The library also asks that you should photograph the artwork only for personal use and without a tripod.
The library staff are doing their best to accommodate the increase of tourists wanting to see the Idiom statue. I use this library often, so I know how busy it can get when people are coming in and out to study there or borrow books on top of a long queue in the middle of the entrance hall.
What is the best time to visit the sculpture?
The Idiom sculpture has become more and more popular in the recent years, which means that there is quite often a queue to get to see it. I go to the main library quite often and I always see at least 15-20 minutes queue, apart from few times in the winter or early spring.
At peak times (mid morning to mid afternoon and weekends) these queues can be up to 45 min – 60 minutes, so be prepared to wait or come back later.
People are waiting to take a photo with the statue and to look inside (and take a selfie!), which can take a little time.
So, if you don’t want to wait for too long, I’d suggest that you arrive as soon as the building opends, which is at 9 am during the week and 1 pm on Monday and Saturday. I’ve also seen less of a queue towards the end of the closing time, like from 6-8 pm. Just bear in mind that the light inside the building is much better during the day time, than evening.
As you are waiting you can find out more about the sculpture by scanning a special QR code, which is on the notice boards close to the queue.
My top Tips for the perfect “Infinity” shot
To get the best photo of the Idiom, you’ll want to switch your phone to a wide-angle lens (0.5x) if you have one. Because the opening is quite narrow, a standard lens often misses the scale of the mirrors.
Turn off your flash! The light will just bounce off the mirrors and create a big white blob in the middle of your “endless” tunnel. I’ve noticed the most striking photos are taken by holding the phone inside the opening—not just pointing at it—but be careful not to drop it!
If you’re using an iPhone, try taking a Live Photo; it allows you to choose the sharpest frame later, which is helpful if your hands are shaking slightly from the vertigo effect.
If you have the time, try to capture a bit of the book textures on the edge to give the photo some “grounding” before the space drops off into infinity.
I’ve taken my photos on my old, but trusty Huawei P30 Pro and since I take square photos, I tried 1:1 ratio, so that I don’t get that much distortion. The light in the library entrance hall is not great at the best of times, so be prepared to edit out yellow undertones from all the library lights if you visit during late afternoon or evening.
How to get to the Idiom sculpture
Location: Mariánské náměstí 98/1, Prague 1, the main entrance hall,
The sculpture is inside the main Prague Municipal Library which is on Marianske Namesti (Square). The nearest underground station and tram station is called ‘Staromestska’ and the library is less than 5 minutes walk from there.
It’s also very close to the Old Town Square, Klementinum Library and the Jewish Quarter, so you can easily walk by to check if there is a big queue or not and either decide it’s worth waiting or carry on visiting other attractions in the meanwhile (see the bottom of this page for more inspiration of what to see nearby).
Opening Times
You can see the Idiom sculpture during the library opening hours, which are from Monday to Saturday. The library is closed on Sundays.
The opening times have been recently changed and Monday and Saturday the library is open from 1 pm – 8 pm and on Tuesday to Friday the opening times are from 9 am – 8 pm.
How much does it cost to visit the sculpture
Since the original intention of the sculpture was to decorate an entrance to the library, the entry to see it is completely free. This is great if you are travelling to Prague on a budget as you can add visiting the Idiom Sculpture as one of the item on your itinerary.
If you want to have a look inside the library, then theoretically you should be a member, but there are often free events, concerts and talks happening inside the library, which are open to everyone.
A little bit more about the author – Matej Kren
Matej Krén (1958) is a Slovak artist originally from Trenčín, who graduated from the Academy of Fine Arts and Design in Bratislava and the Academy of Fine Arts in Prague.
He uses books as a building material to create his sculptural objects and installations. Most of the installations are also interactive in as much as you can look or walk in to them and experience the art firsthand. His other famous installations like Passage (in Bratislava) or Scanner (in Bologna).
What else you can see near Prague Municipal Library
There is a little cafe inside the library building. It’s quite basic and on a smallish side, but it does have a homemade soups, sandwiches and cakes that (in the centre of Prague) are a great value for money. I often go there for coffee and their poppy seed cake is delicious!
As you wait your turn to see the installation, you can also check if there are concerts or films on the lower ground floor.
Several times a year, usually during the Czech national holidays, you can also see the flats that are upstairs above the library. These are beautifully decorated large rooms with private and public areas, which are not normally open to public.
If you are visiting Prague in October, you can see the whole library building used as a projection wall for a Signal Festival and the whole square is turned in to one big light installation. It’s great fun and I always visit as many places as I can during the five days of the festival.
Just across the square is the Klementinum, where you can take a guided tour of the breath-taking Baroque Library. It’s often mentioned as the most beautiful library in the world, and while you can only view it from the doorway to protect the frescoes, the sight of those ancient globes and gold-tooled books is unforgettable.
Right next door is the Clam-Gallas Palace, one of the city’s best-kept secrets. It only recently reopened to the public, and even though the rooms are mostly empty of furniture, the monumental staircase and the incredible ceiling frescoes give you a real sense of 18th-century aristocratic life.
If you fancy a bit of a “secret” thrill, pop into the New Town Hall (Nová radnice) on the eastern side of the square. You can take a tour of one of the Prague’s last remaining Paternoster elevator—a doorless, constantly moving loop that you have to hop in and out of.
I also love to visit Mezi Řádky, a lovely cafe tucked inside the same building. They serve fantastic coffee from their own roastery in Šumava and homemade cakes. I like supporting them because they operate as a social enterprise, providing employment and training for people with mental and learning disabilities. It’s the perfect, quiet spot to sit with a flat white and look over all your photos of the book tower.
This blog post was originally written on 16 September 2024 and last updated on 11 January 2026
