Here is a word of caution regarding the use of single architectural columns. The article was published in "The Civil engineer and architect's journal" in 1848, but the advice can still be heeded.
"The idea of erecting single colossal columns as monuments and architectural objects, was, no doubt, borrowed by the Romans from Egyptian obelisks. Inasmuch as they are both lofty, upright objects, exceedingly well calculated to show at a considerable distance, the column and obelisk agree; but they also differ quite as much, and the difference is decidedly in favor of Egyptian taste. Whereas the obelisk is evidently a monument—a pillar erected to record some fact or facts, or dignify some locality, and is every way fitted by its shape to stand as an insulated, independent monolith, the column plainly expresses itself to be a component member of a fabric; therefore taken by itself alone, meaningless,—in the condition of a verb without a noun, or a noun without a verb. Not only does the column suggest the idea of a super-incumbent architrave, for supporting which it is intended,—'but detached from it, acquires a top heavy and unstable look, the very reverse of that attending the pyrumidum in which the obelisk is made to terminate, and which produces an obtuse apex, instead of the whole being prolonged to a sharp point, like a spire. Except its general proportions as to height, there is nothing that recommends a column tor officiating in lieu of an obelisk. The so employing it manifests very great poverty of invention and barrenness of ideas,—the inability to devise new and more appropriate forms for new purposes. What is characteristic in the column, considered as an architectural member, destined to support either a horizontal entablature or an arch springing from its capital, ceases to have propriety or meaning in a pillar erected merely as either an ornamental object or a votive monument. Such monument may still be a pillar, but it should be one expressly adapted to its peculiar purpose ; therefore, the less it resembles any of the so-called " orders," the better. In this respect, the Rostral column possesses a decided advantage: it shows itself most plainly to be neither more nor less than a trophy pillar. A column of that kind does not look like a fragment of a building. In a building, such form for the columns would be preposterous. To employ Architectural columns as detached monumental pillars, savors of pedantic and puerile conceit, akin to that which during the Elizabethan period fashioned chimney shafts into columns, designed, more orthodoxly than tastefully, according to some one of the "regular" orders."