CREATE TABLE table_203_375 (id DECIMAL, "name" TEXT, "year built" TEXT, "country" TEXT, "town" TEXT, "height" TEXT, "remarks" TEXT)

how many metres is the tallest pylon ?
SELECT "height" FROM table_203_375 ORDER BY "height" DESC LIMIT 1
SELECT "height" FROM "table_203_375" ORDER BY "height" DESC NULLS LAST LIMIT 1