The parish church was built in the 13th century of local limestone, but most of what we can see today is the result of a comprehensive rebuilding in 1865 by architect James Fowler of Louth.
St. Mary's church in Marshchapel is a spectacularly beautiful building constructed of Ancaster stone in the perpendicular style, it was probably completed in 1420 when the bells were hung and is unusual in having been built in its entirety at the one time.
Major internal developments in the 19th century saw the creation of intricate joinery in pews and other items of furniture, but apart from some rebuilding of the chancel also at that time the integrity of the original structure remains intact.
The windows are particularly splendid and delightfully balanced: largely of clear glass as befits the rural ambience, the enormous four light of the west window are complimented by the five lights behind the altar, the three of the aisles, and the two light windows in the clerestory above. The aisle arcades have handsome four-centred arches and the chancel arch matches. Capable of accommodating over 250 people, and with the newly refurbished tower soaring above the extensive churchyard, St. Mary's does full credit to its popular title "Cathedral of the Marshes"
The church interior wood carving is a special point of interest, especially within the chancel roof, the angels, carved rood screen, elaborate pulpit, font cover, and the 134 pew poppyheads. Every one of the poppies are different and all are carved by just one local craftsman.
The tower bells are also of particular interest. Details of the bells can be seen on a description in the entrance porch.