Lord's Castle is a historic house at 211 Hammond Street in Waltham, Massachusetts.

Rufus Lord built the home in 1886 on property purchased from Oel Farnsworth.

Lord, who owned a prominent construction business in Waltham, was known for his work on the Company F State Armory at Sharon and Curtis Streets.

[2] The 2+1⁄2-story masonry house was built as a private residence inspired by Norman castles.

Its most prominent feature is a large three-story circular tower with extensive corbelling and crenellations, details that are repeated on the main block of the house.