The Fish Market building in St Margaret's Street (image 1) is the only medieval market site in Canterbury to survive - those for cattle, corn, butter, reeds, etc have all been lost. It is also one of only two surviving examples of the city's Greek Revival architecture - the other is Canterbury West railway station. This style became popular at the end of the 17th century and start of the 18th centuries. The present building, built in 1822, seems at some stage to have acquired two extra central columns. It currently trades as CJ's Deli Kitchen.
Since the 14th century, fish markets have been authorised on several different sites in the city, including High Street and Burgate. The St Margaret Street building was designed by Jesse White the city surveyor (mentioned on the Christ Church gate page) in 1788, but it took over 30 years to get it approved, financed and built (image 2).
What to see:
fluted Doric columns - count the requisite 20 grooves running down each
the low pitched pediment (the triangular shape above the columns) and generally low, squat appearance typical of Greek Revival work
use of triglyphs (image 3) ie patterns of three vertical small shafts repeated across the frieze; these seem to be later additions - they do not appear on the original 1822 image
the chunky ironwork of the three large semi-circular rear windows (image 4), visible in the 1822 image; to inspect these you need walk round to the rear of the next door premises (now fish and chip shop), avoiding rubbish and enjoying oddly appropriate odours of fish
Sources: Pike (2008); for the 1822 image see Canterbury Cathedral Archives CCA-CC-P/B/2/92