Many examples might be given of buildings with pillars and lintels on the façade, which have no visible modifications of central or end columns to give balance or symmetry to the whole, and yet which are perfectly satisfactory as repeated series and do not demand either such treatment or further continuation, but are complete and finished: London, Trafalgar Square; Rome, Pantheon; Vienna, St. Karl, Barrome Kirche; Berlin, Schillerplatz, etc. These have the centre accented by the superstructure, but there is no discernible modification of the series itself. Examples might be multiplied, but there are sufficient to illustrate the essential stability of repeated vertical units and to contract them with the outward-tending, run-on effect of arches which need various kinds of treatments to finish a series. 165 _Arch Series._ A. 45 Go completely around exteriors: Colosseum, arenas, baptisteries, towers, cloisters, courts, basilicas, tombs. 59 _Series that end:_ B. I. 30 Central arch largest: triumphal arches, doors and windows on façades of churches. II. 1 Central arch smallest: doors on Peterborough Cathedral. III. 4 End arches larger: windows or decorative arches on the walls of buildings. IV. 6 End arches smaller: windows, decorative arches, or arches halfway around a court. V. 6 Arches go obliquely into higher central point and back: decorative arches running into the pointed roof on Romanesque façades. VI. 6 Central arch accented by decoration: windows and gates. VII. 6 End arches in different planes: doors on façades of buildings or in gates. C. 20 Arches go around interiors: up naves and across the apse of churches, halls, and loggias. D. 27 Around the outside of porches, apses, etc.; diminish in size at ends; are carried on in the transepts; motif is carried on, although whole arch is not; end arches are closed, or centres decorated. 7 _Good_ E. 14 Other arrangements: Roman aqueducts (endless); interlacing arches; filled with statues; finished by gables or turrets; bridges (land on each side a sufficient embankment); arches included in large ones. 7 _Poor_ Series not sufficiently finished at the ends; only two arches in series; three arches, with first arch different from the others.