Na dijelu prvotne trase Karolinske ceste, danas šumske ceste između Brestove Drage i sela Slavica, nalazi se 13 krnjih piramida, građenih od velikih kamenih blokova. Svaka je široka i dugačka oko 7 metara te isto toliko visoka. To su fajeri (od njem. pfeiler=stup), koji su služili kao upornjaci strmom vijaduktu (s drvenim podom i ogradom), koji je premošćivao dolinu. Naime graditelj Karolinske ceste Antun Matija Weiss na jedinstven je, ali i neuobičajen način premostio udolinu – umjesto da cestu gradi okolnim, nešto duljim putem i na taj način zaobiđe depresiju, izgradio je vijadukt s priličnim usponom.

Prema zapisanim podacima jedne zime krajem 18. stoljeća teška je kočija s četiri konja i dosta putnika na zaleđenom vijaduktu počela klizati i probivši ogradu pala na tlo, a svi putnici i konji ostali su na mjestu mrtvi. Saznavši za to, graditelj Weiss tada si je oduzeo život. Nakon toga izgrađena je okolna cesta, drveni su dijelovi vijadukta istrunuli, a fajeri još uvijek stoje kao simbol jednog rijetkog, neviđenog i neuspješnog arhitektonskog rješenja.

On a section of the original Caroline road forming today’s forest road between Brestova Draga and the village of Slavica, 13 truncated pyramids built from large stone blocks can be found. Each one measures approximately seven metres in width, length and height. Locals call them “fajeri” (from German pfeiler, meaning “pillar”), and they once served as abutments of a steep viaduct (with a wooden deck and fence) bridging the valley. Antun Matija Weiss, the architect of the Caroline road, solved the issue of the valley in a unique way – instead of making the road take a somewhat longer way round, which would circumvent the depression, he built this considerably tall viaduct.

According to written records, one late-18th century winter, a heavy carriage pulled by four horses and carrying a great number of passengers began sliding across the frozen viaduct and fell to the ground after breaking the fence, instantly leaving all passengers and horses dead. Once Weiss found out about the accident, he took his own life. Afterwards, a surrounding road was built, leaving the wooden parts of the viaduct to rot. Its stone pillars stand as a reminder of a unique, but ultimately failed architectural solution.