The right-of-way of a railway company is subject to special assessments for public improvements, and such assessments constitute a debt due the city which is a paramount lien upon the track of the railway company owning or leasing the right-of-way within the limits of the city. The property of a railway to which a lien for unpaid special assessment has attached may not be released from the lien until the whole assessment is paid. [C97, §816, 828; S13, §791-i, 792-f, 816; SS15, §840-r; C24, 27, 31, 35, 39, § 6009, 6010, 6013; C46, §391.36, 391.37, 391.40; C50, §391.36, 391.37, 391.40, 391A.26; C54, 58, 62, 66, 71, 73, §391.36, 391.37, 391.40, 391A.29; C75, 77, 79, 81, §384.64 ] Referred to in §331.384 , 357E.11A , 358.16 , 364.13B