The original pavement on the streets of the Old Town and Lesser Town and Hradčany was made of quartzite. Simply put, sandstone has metamorphosed in such a way that its dominant component is quartz. This composition makes this stone hard but brittle.

Later, granite, which is more robust and has a rougher surface, was used to pave the streets so it’s not slippery after raining, like quartzite paving. The early paving was laid in a semicircular grid but later in a parallel grid.

The oldest cobble stones are called “cat heads”. Quartzite is fragile, and when heavy horse-drawn wagons drove over such pavement, they popped up while driving over them, causing small pieces of paving to break off at the edges of the blocks. Chipping off the edges of the paving stones created a raised middle section and various irregularities on the lowered edges, which with a bit of imagination, resemble the silhouette of a cat’s head.