How high was the highest building in feet in the city of cologne?
CREATE TABLE "timeline_of_tallest_buildings" (
  "name" text,
  "city" text,
  "height_m" real,
  "height_ft" real,
  "floors" real,
  "years_as_tallest" text
);
SELECT MAX("height_ft") FROM "timeline_of_tallest_buildings" WHERE "city"='cologne';