Constructed between 1593 and 1597, the Triangle Lodge was designed by Sir Thomas Tresham.

Built as a monument to his Roman Catholic beliefs, Tresham revered the number three, representing the Holy Trinity, which is evident in the layout of the Lodge. Comprised of three floors, including the basement, three sides each 33 feet long, and three windows on each side for each floor. On every side of the building is a different Latin text from the Bible, each 33 letters long. The inscriptions are as followed:

-Aperiatur terra & germinet Salvatorem: “Let the earth open and … bring forth salvation” (Isaiah 45:8)

-Quis separabit nos a charitate Christi?: “Who shall separate us from the love of Christ?” (Romans 8:35)

-Consideravi opera tua, Domine, et expavi : “I have contemplated thy works, O Lord, and was afraid” (Habakkuk 3:2)

Each floor of this folly is comprised mainly of a hexagonal room, which leaves three triangles in each corner. In one of these corners is a spiral staircase, the other two are small rooms. Atop each wall sits three gargoyles, and above them are three pointed gables. Cast in the stone of the outer two gables of each of the walls is a symbol of importance. Among the emblems are the Seven-branched Candelabrum, the Seven Eyes of God, a Hen and Chickens, a Dove and Serpent, the Hand of God touching a globe, and a Pelican in her Piety.

A broken inscription across the three middle gables, which are actually sundials, reads: Respicite, Non Mihi Soli Laboravi, “Mark ye, not for myself alone have I toiled.” Atop the three gables on each side is a three-sided obelisk, reaching toward the sky. The obelisk, too, has symbols adorning each side, including the Christogram “IHS”, Iesus Hominum Salvator (“Jesus, Savior of men” in Latin), a lamb and cross, and a chalice.

The building facade is covered in seemingly random numbers, Tresham’s initials, and a multitude of heraldic shields and crests. The trefoil, or three-leafed clover, features prominently on the building, this is because the trefoil is the main symbol of the Tresham family crest. Each of the windows on the second floor are trefoils with triangular panes within. Above the entrance is the number 5555, though the numbers’ appearance is odd, leaving some historians to speculate that it once read 3333.

Above the door, but underneath the Tresham coat of arms lies the inscription: Tres testimonium dant, “The number three bears witness.” Some think that the inscription could mean “Tresham bears witness,” considering “Tres” was the pet name given to him by his wife. Successfully nestled away in the countryside to prevent discovery by Protestant authorities, the Triangular Lodge survived the period of persecution of English Catholics.