Picture to come.
Building
Market
A market was a regular weekly gathering for buying and selling, held in a street, open square or churchyard, often beside a castle or church. By 1066 the right to hold one was treated as a royal franchise, and lords took the tolls and stallage. Traders set up temporary trestle stalls under awnings. Kent alone had at least fifteen markets before 1200; royal grants multiplied rapidly after that date, and systematic recording of market charters begins in 1199.
Caveats (confidence: high)
Physical layout of 12th-century market places is poorly documented; many markets were 'prescriptive', with no surviving charter.
Sources: archives.history.ac.uk · kentarchaeology.org.uk
Built from
Not built by a house: it comes with the town.