Beyond the Baths: Secrets of Roman Building Materials

Have you ever wondered, in a world dominated by concrete and synthetic materials, what the Romans used over two thousand years ago to produce enduring buildings, all without the aid of modern technology?

Crafting from Nature

Roman Britain had a variety of small workshops in every town, with the majority of the goods being produced there to satisfy regional demands. The Romans used natural resources and transformed them into purpose-fit building materials. From the rock and clay in the ground, timbers in the forest, to sand on the seashore, they selected materials wisely.

Experienced craftsmen then made the raw materials into durable building components. For instance, tufa, which is a porous sedimentary rock created in mineral springs. Its sponge-like texture, which was both light and robust, made it an ideal material for creating vaulting structures. Due to the tufa's special characteristics, craftsmen used it to create wedge-shaped voussoirs that, when placed next to each other, supported beautiful vaults or arches.

Tufa from the Great Bath, Roman Baths

Functional and Aesthetic

The Romans were more than just engineers; they were artists who celebrated both beauty and function. The colorful and well-designed mosaics that adorned their rooms were a clear sign of this mix.

Mosaics have a long and interesting past. They started in Mesopotamia in the 3rd millennium BC and spread to places like Ancient Greece and Rome before being used all over the world. In the Roman Baths, mosaic art is a burst of color. The secret? The tesserae made from different stones including hematite, pyrite, yellow iron oxide, and local Bath Stone. Bath Stone, which is also called freestone, got its name because it is soft and easy to cut in any direction. Since Roman and Medieval times, it's been a go-to for building across southern England. From churches to homes, its honey-colored beauty remains. Even today, Bath's Georgian buildings shine, thanks to this ancient material.

Bath Stone (photo credit: The Open University Geological Society)

Sea Horse Mosaic, Roman Baths

Materials from Far and Wide

As the Roman Empire expanded, a wide variety of building materials flowed in from diverse lands, bringing abundant supplies. A good example is the Roman Baths, which made use of both native materials and imported ones.

Due to a scarcity of natural marble in England, this expensive stone was imported from Spain or Southern Italy, giving luxury to the construction. Purbeck marble stepped in as a low-cost replacement. It has a polished shine while not being real marble. This fossiliferous limestone from Dorset, England, sometime contains fossils of ancient freshwater organisms. This is a Labrum fragment made of Purbeck marble found at the Roman Baths to hold water, which was used to cleanse before entering the bath or to cool down in the Caldarium (hot bathroom).

Labrum fragment made of Purbeck marble

Xingyue Yang Placement Student

古罗马建筑的秘密

生活在一个被钢筋水泥和复合材料包围的世界，你是否想过，两千多年前，没有任何现代科技的罗马人使用什么材料去建造房屋呢？

取自自然

罗马不列颠的每一个小镇都有不同的小作坊，生产不同种类的产品以满足本地需求。罗马人利用自然资源，并将其改造加工成不同部件的建筑材料。地下的岩石与粘土，森林中的树木，海边的沙子，都是他们充满智慧的选择。

在完成选择材料后，经验丰富的工匠将原材料加工成坚固耐用的建筑构件。比如说，Tufa，这是一种多孔的沉积岩，形成于矿物质泉水之中。Tufa如同海绵般的结构赋予了它兼顾轻巧和坚固的特点，使之成为修建拱顶的理想材料。由于这种特性，工匠们将Tufa制成楔状穹顶部件，当一个个部件紧密相连就构成了美观的圆形拱顶或者拱门。

在罗马巴斯浴场发现的 Tufa

实用与美观

罗马人不仅仅是建筑工程师，更是兼顾美观与实用性的艺术家。汇聚设计巧思的五颜六色的马赛克便是最好的例子，它常用于室内装饰。

马赛克历史悠久，起源于公元前三世纪的美索不达米亚，然后传播到古希腊和古罗马，最终全世界都能发现它们的身影。在罗马巴斯浴场，马赛克迸发出绚烂的艺术之光。五颜六色的马赛克由不同石料制成的 tesserae 组成，包括赤铁矿、黄铁矿、黄色氧化铁和当地的Bath Stone。Bath Stone，又称 "freestone"，因其质地柔软、易于从任何方向进行切割而得名。从罗马时期和中世纪起，在英格兰南部地区，Bath Stone 便成为常见的建筑材料。无论是神圣的教堂，还是日常的民居，都可以找到Bath Stone的如同蜂蜜般的黄色外观。时至今日，巴斯城中的乔治亚风格建筑依然熠熠生辉，这要归功于这种历史悠久的材料。

Bath Stone (图片来源: The Open University Geological Society)

罗马巴斯浴场中的海马装饰马赛克

来源丰富的原料

随着罗马帝国的扩张，建筑材料的原产地更加多样，带来了丰富且充足的供给。罗马巴斯浴场就是一个好的例子，同时使用了本地和进口的材料。

在英格兰本土，天然大理石十分稀少，这种昂贵的石材往往从今天西班牙或者意大利南部进口，属于极其奢侈的建筑材料。Purbeck marble 是天然大理石的平价替代品。这种石材虽然不是真正的大理石，但打磨后也有抛光的质感。这种产自英格兰 Dorset 的石灰岩化石，有时含有古代淡水生物的化石。下图是在罗马巴斯浴场发现的由 Purbeck marble 制成的 Labrum 的文物遗存，用于装盛清水，在进入浴场前用来清洁，或在 Caldarium（热浴室）中用来降温。