Rows of toilet paper, bathroom vessels of all types, shapes and sizes and cistern pulls made of china, wood and brass are the stars of the show at this museum of relief in the Czech capital.
"We bought a 10th-century fortress near Prague and discovered a historic toilet there," says Jan Sedlacek, a 59-year-old civil engineer and head of the Museum of Historical Chamber Pots and Toilets.
"That's how it started: we wanted to know how people did it back then," he told AFP, pinpointing the moment he became a toilet collector.
The museum, which opened at the fortress in 2010 and moved to Prague this year, now boasts 2,000 items, which Sedlacek says makes it the world's largest ahead of similar venues in India and Spain.
"We keep looking for items with history," he said, pointing to a bedpan made out of a World War II German army helmet.
The collection also features a hard-to-get Japanese "Washiki" squat toilet, a bedpan built for Napoleon and portable urinals used by women during long sermons delivered by the 17th-century French preacher Louis Bourdaloue.
"The most precious exhibits are the price of a very decent car," Sedlacek said.
Employing his wife and some of his six children at the museum, Sedlacek has spent around 10 million koruna (360,000 euros, $480,000) of his own money on the collection.
Spanning two storeys of an old house, the museum welcomes around 600 people a month -- revealing secrets old and new.
"Some see a bedpan with a lid and cry: 'Look, Jesus, we've been eating soup out of this our whole lives!'" Sedlacek said.