CREATE TABLE table_204_929 (id DECIMAL, "location" TEXT, "name of mill and\ grid reference" TEXT, "type" TEXT, "maps" TEXT, "first mention\ or built" TEXT, "last mention\ or demise" DECIMAL)

what location has the most maps ?
SELECT "location" FROM table_204_929 GROUP BY "location" ORDER BY SUM("maps") DESC LIMIT 1
SELECT "location" FROM "table_204_929" GROUP BY "location" ORDER BY SUM("maps") DESC NULLS LAST LIMIT 1