In 1628 the Irish Society was ordered to erect guard and sentinel houses, of which two are yet remaining; and of the several bastions the north western was demolished in 1824, to make room for the erection of a butter market, and in 1825 the central western bastion was appropriated to the reception of a public testimonial in honour of the celebrated George Walker. A few guns are preserved in their proper positions, but the greater number are used as posts for fastening cables and protecting the corners of streets. The houses are chiefly built of brick: the entire number in the city and suburbs in 2947. The city is watched, paved, cleansed, and lighted with gas, under the superintendence of commissioners of general police, consisting of the mayor and 12 inhabitants chosen by ballot; the gas works was erected in 1829, at an expense of £7000, raised in shares of £11. Water is conveyed to the town across the bridge by pipes, from a reservoir on Brae Head, beyond the Waterside in the parish of Clondermot; the works were constructed by the corporation under an act of the 40th of Geo. III., at a total expense of £15,500 and iron pipes have been laid down, within the last few years. The bridge, a celebrated wooden structure erected by Lemuel Cox, an American, in lieu of a ferry which the corporation held under the Irish Society, was begun in 1759 and completed in the spring of 1791.It is 1069 feet in length, and 40 in breadth: the piles are of oak, and the head of each is tenoned into a cap piece 40 feet long and 17 inches square supported by three sets of girths and braces; the piers, which are 16½ feet apart, are bound together by thirteen string pieces, equally divided and transversely bolted, on which is laid the flooring; on each side of the platform is a railing 4½ feet high, also a broad pathway provided with gas lamps. Near the end next to the city a turning bridge has been constructed in place of the original drawbridge, to allow of the free navigation of the river. On the 6th of Feb., 1814, a portion of the bridge extending to 350 feet was carried away by large masses of ice floated down the river by the ebb tide and a very high wind. The original expense of its erection was £16,594, and of the repairs after the damage in 1814 £18,208 of which latter sum, £15,000 was advanced as a loan by Government; the average annual amount of tolls from 1831 to 1834 inclusive, was £3693. Plans and estimates for the erection of a new bridge nearly 200 yards above the present, have been procured; but there is no prospect of the immediate execution of the design. A public library and news room commenced in 1819 by subscription and established on its present plan in 1824 by a body of proprietors of transferable shares of 20 guineas each, is provided with about 2660 volumes of modern works and with periodical publications and daily and weekly newspapers; it is a plain builting faced with hewn Dungiven sandstone, erected by subscription in 1824, at an expense of nearly £2000 and, besides the usual apartments, contains also the committee room of the Chamber of Commerce. The lower part of the building is used as the news room to which all the inhabitants are admitted on payment of five guineas annually. A literary society for debates and lectures was instituted in 1834 and the number of its members is rapidly increasing. Concerts were formerly held at the King's Arms hotel, but have been discontinued. Races are held on a course to the north of the town. Walker's Testimonial, on the central western bastion, was comleted in 1828 by subscription, at an expense of £1200: it consists of a column of Portland stone of good proportions, in the Roman Doric style, surmounted by a statue of that distinguished governor by John Smith, Esq., of Dublin; the column is ascended by a spiral staircase within, and, including the pedestal, is 81 feet in height in addtion to which the statue measures nine feet.
The city is in the northern military district and is the head quarters of a regiment of infantry which supplies detachments to various places: the barracks are intended for the accommodation of four officers and 320 men, with an hospital for 32 patients, but from their insufficiency a more commodious edifice is about to be erected, for which ground has been provided in the parish of Clondermot.
The deanery, a large unadorned edifice of brick, was built in 1833 by the Rev. T. B. Gough, the present dean, at an expense of £3421. 16s. 8½d., to be reimbursed by his successor. Adjacent to the city wall on the west is a chapel of ease, a rectangular building, erected by Bishop Barnard, whose descendant, Sir Andrew Barnard, became the patron; the chaplain's original stipend of £50 is now paid out of the property of Wm. J. Campbell, a minor, who claims the advowson. A free church was built on the north of the city by Bishop Knox, in 1830, at an expense of £760; and a gallery was erected in 1832, at a further expense, including the cost of a vestry room and the introduction of gas, of £145, raised by subscription. The R. C. chapel occupies the site of the monastery of St. Columb, and is situated in a street called the Long Tower, from the lofty round tower which formed the belfry of the Dubh-Regles, the original church, built by St. Columb. This chapel was completed in 1786 at an expense, including the cost of some addition in 1811, of £2700, of which £210 was contributed by the Earl of Bristol, and £50 by the corporation.
The Presbyterian meeting-house in Meeting house row, has a chaste and handsome front of which the pediment and corners are of Dungiven freestone; it is supposed to have been built about the yeare 1750. The Primitive Wesleyan Methodist chapel in the same street was originally a store, which was used by Wesley on his visit to this city in 1763; his congregation built the Wesleyan Methodist chapel in 1783, but on the separation taking place, the Primitive Methodists returned to their former place of worship; part of the building is stell let for a store, and the chapel is used as a Sunday school between the intervals of divine service, for which the dean pays a rent of £20.
The parish school originated in an act of the 28th of Hen. VIII., confirmed by one of the 7th of Wm. III.; the present building situated without the walls, was erected in 1812 through the liberal contributions of Bishop Knox and the trustees of Erasmus Smith's charity, the latter of whom allow annually £30 for the boys' and £15 for the girls' school, and, in addition, the girls' school is aided by annual grants of £40 and £10 late currency from the Irish Society and the Bishop of Derry respectively; there are about 108 boys and 97 girls, who except 20 of the boys who are free scholars, pay one penny each weekly.
In addition to the Ecclesiastical buildings already recorded here was also a Franciscan mendicant friary of unknown foundation, with a churchyard containing about three acres, the site of which is now occupied by Abbey street and others, and of which the foundations were discovered a few years ago by some workmen, but no vestiges of any of these buildings are now remaining. The only religious house preserved on the erection of the new city was the church of St. Augustine, which was repaired and used prior to the erection of the present cathedral, after which it was known as "the little church;" its site is now occupied by the bishop's garden. A small square tower was built by O'Dogherty for O'Donell, in the 15th or 16th century, but no vestige of it can now be traced. Near the Roman Catholic chapel, outside the walls, are St. Columb's wells, originally three in number and called by separate names, but one of which is dried up; but the water, though considered in remote parts of the island a specific for diseases of the eye, is here held in little repute. In the centre of St. Columb's lane, adjacent to the wells, is St. Columb's stone, on each side of which are two oval hollows artificially formed, concerning which various legends are related; the water deposited by rain in these hollws is believed to possess a miraculous power in curing various diseases.