CREATE TABLE table_203_28 (id NUMBER, "year" NUMBER, "competition" CLOB, "venue" CLOB, "position" CLOB, "event" CLOB, "notes" CLOB)

where was the only 5km event held ?
SELECT "venue" FROM table_203_28 WHERE "event" = '5 km'
SELECT "venue" FROM "table_203_28" WHERE "event" = '5 km'