The lien for the things aforesaid, or work, shall attach to the buildings, erections or improvements for which they were furnished or the work was done, in preference to any prior lien or encumbrance or mortgage upon the land upon which said buildings, erections, improvements or machinery have been erected or put; and any person enforcing such lien may have such buildings, erections or improvements sold under execution, and the purchaser may remove the same within a reasonable time thereafter; provided, that nothing contained in this section shall be so construed as to allow any such sidewalk as is mentioned in sections 429.010 to 429.340 to be so sold under execution or so removed.