Tourists who visit the Hippodrome in Istanbul are usually unaware that the far end is in fact supported by Byzantine masonry, as the land falls away on that side. The construction is called the sphendone. These days a Turkish official building sits on top of it.
Here’s a particularly nice photograph of the sphendone, as it appeared in June 1935. I found it at DOAKS here, part of the Nicholas Artamonoff collection (Negative Number: RA64; Reaccession Number: ICFA.NA.0021)
Very sharp, and very clear! Lovely. I must go and look at the sphendone if I can ever return to Istanbul!