[3] Hammatt Billings, Boston architect, illustrator, and sculptor, originally conceived the monument as a 150-foot-tall (46 m) structure comparable to the Colossus of Rhodes.

Shortly before his death in 1874, Billings reduced the size of the monument, which was to be made entirely of granite quarried in Hallowell, Maine.

[4] The project was then passed to Billings' brother Joseph who, along with other sculptors including Alexander Doyle, Carl Conrads, and James Mahoney, reworked the design, although the basic components remained.

Upon the four buttresses also are seated figures emblematic of the principles upon which the Pilgrims founded their Commonwealth; counter-clockwise from the east are Morality, Law, Education, and Liberty.

Each was carved from a solid block of granite, posed in the sitting position upon chairs with a high relief on either side of minor characteristics.

On the face of the buttresses, beneath these figures are high reliefs in marble, representing scenes from Pilgrim history.