The church was finished about 1240. It is one of the four round churches still remaining in England. Its plan is that of a central round tower, supported by six beautiful clustered columns, crossed by a nave and transepts. Notwithstanding the lapse of ages, and although its beauties were for centuries hidden beneath a variety of hideous excrescences, it remains to-day one of the best specimens of early Gothic architecture extant. In 1682, 1695, 1706, 1737, and 1811 extensive repairs were made. In 1828 the exterior was thoroughly restored and recased with stone, and several unsightly structures that impeded the view of the church were removed. All of these so-called restorations were, however, but partial in extent. Many outrageous additions and much meretricious ornamentation, added at various epochs, were allowed to remain. Finally, in 1845, steps were taken looking to a thorough renovation and restoration of the venerable pile. The purity of the marble columns had been sullied by several coats of paint and whitewash, while many of the foliated capitals of the columns supporting the "Round" bore traces of gilding. These latter were scraped and cleaned; an eight-feet-high oak wainscot was removed; light, movable seats were substituted for the heavy pews of Charles II.'s time that encumbered the Round; the pavement was lowered to its original level, thus revealing the bases of the columns; the organ (built by the famous Father Smith in the reign of Charles II.) was removed to its present position in the choir, and the whole interior, by means of these and other extensive changes, was exhibited in its pristine purity. It is difficult to understand the crass stupidity which blocked up exquisite Norman windows, covered carved capitals with a thick coat of cement, closed many of the arches with wooden partitions, planted a cumbrous pulpit and reading-desk immediately under the dome, and hid the noble groined ceiling behind a shell of flat, whitewashed boarding. In the course of these repairs much of the marble-work was found to require renewal, for replacing which some old quarries in the Isle of Purbeck, unworked for generations, were reopened.