The mix of architectural styles in the Prison Tower is the result of several
rebuildings. The tower was originally built as part of the now-destroyed Ulica
Długa Gate that was erected in the second half of the 14th century as part of
the medieval fortifications of the Main Town.

In the 15th and 16th centuries, the tower was heightened several times and the
surrounding buildings altered accordingly. When the new fortifications were
built in 1571–6 the entire complex lost its purpose. It began to be used as a
prison, court and torture chamber.

It was remodelled for its new purpose in 1604 by Antonis van Opbergen, who gave
it a northern Mannerist form, and by Willem van der Meer, who added decorative
detail. The tower was the scene of many blood-curdling interrogations. There is
a whipping post on the western wall, which was also the site of many executions.
At the turn of the 20th century, in accordance with the new functions of the
buildings, a stonecutter’s workshop was installed in the courtyard.

The Prison Tower now houses the Amber Museum.