There are thousands of industrial chimneys in the Czech Republic, with many dating back to the late 19th Century - most are no longer used and a group of enthusiasts spend their weekends climbing the structures. Alastair Lawson joined them in Zelezny Brod, but soon regretted it.
I am 40m (130ft) up a 120-year-old chimney in the north-east of the Czech Republic and I am having a minor panic attack. My legs feel like lead weights as I look down on the tiny figures on the ground below me.
"Are you coming up or going down?" asks my guide, Martin Vystejn, as I cling for dear life on to the ladder.
The fear gripping me is so overpowering that my inclination is to do neither and remain suspended in mid-air about two-thirds of the way up the 52m (170ft) disused industrial chimney.
The other climbers seem unruffled by my agony and continue nonchalantly to make their ascent, neatly bypassing me on the ladder as I scuttle downwards.
So how did I end up in this predicament?