When I was walking around the streets where my dad is in a care home, I came across this interesting interlocking flat brick arch lintel. A bit of a mouthful you might say but it was so unique that I quickly took a photo of it before the owners saw me. I have never seen bricks of this shape been used before and just as with any stone or brick arch, the strength of the arch depends on the mortar joints between each unit being in full contact and the mortar not deteriorating. If it does, then you get slippage occurring to the arch and you can see this has happened to the right hand lintel and has caused cracking to the brickwork above.