Guide Digest

The Geometric Design of Castel del Monte

A detailed study is presented of the sructural design of Castel del Monte, specifically how the medieval architects came up with the concept and the design.

The perfect forms and layout of the masonry at Castel del Monte is evidence that geometry is the theme and the guiding hand in the design of this castle.

Scholars and writers have invariably come to this conclusion, often speculating on what may have been the design process. This study identifies the geometric design for the plant layout of Castel del Monte, thus providing a unique window in the design knowledge and means at the height of the Middle Ages.

The presentation is divided in various sections, as indicated in the home page and outlined below.

1. Plant Concept Design .......... Open
2. Plant Modified Design .......... Open
3. Mathematical Model ............ Open
4. Cross Vault Technology ....... Open
5. Portal Wing Design ............. Open
6. Elevation Design ................ Open
7. Papers, Articles, etc ............ Open
8. Photo Album ...................... Open

Section I — Plant Concept Design

The design starts with the ground plan. This is the key portion of the overall design, because it addresses the fundamental question of cross-vault construction and their support for a stable edifice.

This is the creative process where a series of geometric constructions follow starting from a square and ending up with an octagonal plant with octagonal towers at each corner and an octagonal courtyard. This gives the design the forms and look that is seen nowadays in the plant layout.

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Section II — Modified Plant Dsign

The modification is a small enlargement of the towers, followed by a small relocation of the tower and a readjustment to the walls. The modification was nade by means of geometric manipulations with the objective of retaining the dimension of the cross vault as established in the concept design. The modification changes only slightly the towers, leaving inaltered the overall form of the plant design.

This is different from other changes that followed later in the design directed at specific portions of the castle, such as the modification at the entrance wing of the castle to accommodate a portal with portcullis.

The modification is an is key part of the plant design that brings the measures in the design model to match exactly the measurements at the castle. It also explains many details such as the seemingly irregular form of the tower octagon, the roof spandrels discovered by H. Götze.

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Section III — Mathematical Model of the Plant Design

The design outlined in sections I and II is a geometric algorithm that yields a complete layout of the plant, including dimensions, starting with a simple geometric form, a square.

The geometric algorithm has a parallel mathematical algorithm: a sequence of dependent mathematical relationships based on the geometric forms. This sequence starts with an assigned measure, the diagonal of the base square, and yields the measures for any structural form of the plant, matching the actual dimensions exactly.

The mathematican model has been essential in the analysis that has identified the true geometric design model. Even more significantly, it has served to identify the unit of linear measurement used at Castel del Monte, a foot that measures 0.302 meters.

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Section IV — Cross Vault Technology

The study of the plant design of Castel del Monte has included research on the construction technology of ribbed cross vaults perfected at the height of the Middle Ages. This technology was also used for the cross vault construction at Castel del Monte.

However, the uniqueness at Castel Del Monte is the way eight similar cross vaults are set in a circular disposition inside the frame of the Islamic eight pointed star to resolve the issue of cross vault lateral thrusts. This is in contrast to other solutions pursued at the time such as in the construction of tall cathedrals.

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Section V — Portal Wing Design

An elaborate portal was added for the entrance to the caste to the octagonal side of the castle facing east. The addition of this portal caused a small structural adjustment of the plant design along this wing of the plant. The room cross vault was moved by a foot toward the center of the plant, resulting in a distortion in the octagonal perimeter of the courtyard.

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Section VI — Elevation Design

The diagonal of the cross vault base square is key dimension in the plant design; but it is also a measurement that determines the height of the vault because the cross vault diagonal rib that spans this diagonal has a semicircle form in the medieval technology or ribbed cross vault construction.

This has led to inquire in the height of the vaults and the rooms, searching for geometrical models that may have been used for determining these heights and how these rlated bearing structures are disposed on the upper floor compared to the ground floor.

The examination had to wait until an opportunity presented to collected relevant room height data in 2018.

The analysis has indeed revealed geometric models that were used in the vertical configuration of vaults and rooms. The research has revealed also structural issues for the room enlargement on the upper floor, as well as a construction blunder related to the upper molding on the ground floor.

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Sectione VII — Papers, Articols, Writings, etc.

Collection of various material of significance in this structural study of Castel del Monte geometry. Most noteworthy is an unpublished paper that ties together the plant concept design and the plant modified design in a unified narrative within the contexts of the mystical, religious, and cultural background of the Middle Ages.

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Section VIII — Album foto

Collection of photos in the course of a long study on Castel del Monte.

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