From the Middle Ages until the 18th century, in Europe ropes were constructed in ropewalks, very long buildings where strands the full length of the rope were spread out and then "laid up" or twisted together to form the rope. The cable length was thus set by the length of the available rope walk. This is related to the unit of length termed "cable length". This allowed for long ropes of up to 300 yards long or longer to be made. These long ropes were necessary in shipping as short ropes would require splicing to make them long enough to use for sheets and halyards. The strongest form of splicing is the short splice, which doubles the cross-sectional area of the rope at the area of the splice, which would cause problems in running the line through pulleys. Any splices narrow enough to maintain smooth running would be less able to support the required weight.