From the prominent position it occupies in all monumental buildings, the capital has always been the favourite feature selected for ornamentation, and consequently it has become the clearest indicator of any style.
The two earliest Egyptian capitals of importance are those which are based on the lotus and papyrus plants respectively, and these, with the palm tree capital, were the chief types employed by the Egyptians, until under the Ptolemies in the 3rd to 1st centuries BCE, various other river plants were also employed, and the conventional lotus capital went through various modifications.
The Achaemenid Persian capital belongs to the third, bracketed class above mentioned; the brackets are carved with the lion or the griffin projecting right and left to support the architrave, and on their backs carrying other brackets at right angles to support the cross timbers. The profuse decoration underneath the bracket capital in the palace of Xerxes at Susa and elsewhere, serves no structural function, but gives some variety to the extenuated shaft.
The earliest Aegean capital is that shown in the frescoes at Knossus in Crete (1600 B.C.); it was of the convex type, probably moulded in stucco. Capitals of the second, concave type, include the richly carved examples of the columns flanking the 'Tomb of Agamemnon' in Mycenae (c. 1100 BCE): they are carved with a chevron device, and with a concave apophyge on which the buds of some flowers are sculpted.
The Doric capital is the simplest of the five Classical orders: it consists of the abacus above an ovolo molding, with an astragal collar set below. In the Temple of Apollo, Syracuse (c. 700 BCE), the echinus moulding has become a more definite form: this in the Parthenon reaches its culmination, where the convexity is at the top and bottom with a delicate uniting curve. The sloping side of the echinus becomes flatter in the later examples, and in the Colosseum at Rome forms a quarter round.
In the Ionic capital spirally coiled volutes are inserted between the abacus and the ovolo. In the Ionic capitals of the archaic Temple of Artemis at Ephesus (560 BCE) the width of the abacus is twice that of its depth, consequently the earliest Ionic capital known was virtually a bracket capital. A century later, in the temple on the Ilissus, the abacus has become square.
The foliage of the Greek Corinthian capital was based on the Acanthus spinosus, that of the Roman on the Acanthus mollis. They are genereally carbed in two ranks or bands, like one leafy cup set within another. One of the most beautiful Corinthian capitals is that from the Tholos of Epidaurus (400 B.C.); it illustrates the transition between the earlier Greek capital, as at Bassae, and the Roman version.
In Roman architectural practice, capitals are briefly treated in their proper context among the detailing proper to each of the 'Orders', in the only complete architectural textbook to have survived from classical times, the Ten Books On Architecture, by Marcus Vitruvius Pollio, better known just as Vitruvius, dedicated to the emperor Augustus. The various orders are discussed in Vitruvius' books iii and iv. Vitruvius describes Roman practice in a practical fashion. He gives some tales about the invention of each of the Orders, but he does not give a hard-and-fast set of canonical rules for the execution of capitals.
Two further, specifically Roman orders of architecture have their characteristic capitals, the sturdy and primitive Tuscan capitals, typically used in military buildings, similar to Greek Doric, but with fewer small moldings in its profile, and the invented Composite capitals not even mentioned by Vitruvius, which combined Ionic volutes and Corinthian acanthus capitals, in an order that was otherwise quite similar in proportions to the Corinthian, itself an order that Romans employed much more often than Greeks.
The adoption of Composite capitals signals a trend towards freer, more inventive (and often coarser) capitals in the Late Antique.
Byzantine and Gothic capitals
Byzantine capitals are of endless variety; the Roman composite capital would seem to have been the favourite type they followed at first: subsequently, the block of stone was left rough as it came from the quarry, and the sculptor, set to carve it, evolved new types of design to his own fancy, so that one rarely meets with many repetitions of the same design. One of the most remarkable is the capital in which the leaves are carved as if blown by the wind; the finest example being in Santa Sophia, Thessalonica; those in the Cathedral of Saint Mark, Venice specially attracted Ruskin's fancy. Others appear in St Apollinare-in-Classe, Ravenna.
The capital in San Vitale, Ravenna shows above it the dosseret required to carry the arch, the springing of which was much wider than the abacus of the capital.
The Romanesque and Gothic capitals throughout Europe present as much variety as in the Byzantine and for the same reason, that the artist evolved his conception of the design trom the block he was carving, but in these styles it goes further on account of the clustering of columns and piers.
The earliest type of capital in Lombardy and Germany is that which is known as the cushion-cap, in which the lower portion of the cube block has been cut away to meet the circular shaft. These early types were generally painted at first with various geometrical designs, afterwards carved.
In Byzantine capitals, the eagle, the lion and the lamb are occasionally carved, but treated conventionally. In England and France, the figures introduced into the capitals are sometimes full of character. These capitals, however, are not equal to those of the Early English school,in which the foliage is conventionally treated as if it had been copied from metalwork, and is of infinite variety, being found in small village churches as well as in cathedrals.
Renaissance and post-Renaissance capitals
In the Renaissance period the feature became of the greatest importance and its variety almost as great as in the Byzantine and Gothic styles. The flat pilaster, which was employed so extensively in the Renaissance, called for a planar rendition of the capital, executed in high relief. This affected the designs of capitals. A traditional 15th century Early Renaissance variant of the Composite capital turns the volutes inwards above stiffened leaf carving. In new Renaissance combinations in capital designs, most of the ornament can be traced to Roman sources.
The Renaissance was as much a reinterpretation as a revival of Classical norms. The volutes of Greek and Roman Ionic capitals lie in the same plane as the architrave above them. This may create an awkward transition at the corner, where, for example, the designer of the Temple of Athene Nike on the Acropolis, brought the outside volute of the end capitals forward at a 45-degree angle. The problem was more satisfactorily solved by the 16th century Renaissance architect Sebastiano Serlio, who angled outwards all the volutes of his Ionic capitals. Since then, the use of antique Ionic capitals, instead of the Serlian version, has tended to lend an archaic air to the entire context, as in Greek Revival
Within the bounds of decorum, a certain amount of inventive play has always been acceptable within the classical tradition. When Benjamin Latrobe redesigned the Senate Vestibule in the United States Capitol in 1807, he introduced six columns that he 'Americanized' with ears of corn (maize) substituting for the European acanthus leaves. As Latrobe reported to Thomas Jefferson in August 1809,