Some Major Stylistic Periods of Medieval Art and Architecture

                                                                                                                     Castles, Fortifications and Towers.   
 Denmark, Sweden, Norway; 
               1. Viking                                  (c900-1000)                    Fyrkat, Trelleborg,
               2. Norman                               (c1020-1190)                  Asserbo, Helsingborg(*), Nyborg, Kalundborg, StegeSteinvikholm,
                                                                                                      Sverresborg (Trondheim),  Absalon's castle (Copenhagen), Munkholmen
               3. Motte and Bailey                  (c1250)                           Bohus(**)
               4. Geometric                            (c1130-1250)                 Varberg , Lodose, Sverresborg (Bergen), Alvsborg
               5. Lancet                                  (c1180-1275)                 Sonderborg, Vordingborg, Hjelm (O), Orkild, Korsor, Kolding
               6. Regional Scandinavian          (c1100-)                        Jaegerspris (reconstruction) , Bornholm, Sjorring, Kalo, Borren,
                                                                                                      Bastrup, Akershus, Hakon's Hall (castle), Tonsberg, Kirkenes,
                                                                                                      Tromso, Narvik, BodoScansin

(*)      Now part of Sweden, but, at the time of construction, within the Danish province of Scania.
(**)     Now part of Sweden, but, at the time of construction, belonging to a disputed Norwegian/Danish corridor, north and south of Gothenberg, the current
building bears some features of the Motte and Bailey design, although built by the Norwegians at a later date.  
(***)    Lines of fortifications; (i). Hjelm, Vordingborg, Nyborg, Bastrup(?). (ii). Borren, Hjelm O, Kalo, Fyrkat, Sjorring. (iii). Orkild, Vordingborg, Stege.
                                              (iv). Sonderborg, Orkild, Korsor.
            Circles of fortifications; (i). Kalundborg, Jaegerspris, Hjelm O, Asserbo. (ii). Vordingborg, Hjelm, Hjelm, (?).  (iii). Osterlars, Nyker, Olsker, Nylars.
            Square of fortifications; Asserbo, Roskilde, Helsingborg, Barakkebro(?). 

                  The classification depends on observable features in the designs of fortifications, the dating of their construction and their geographic position. This seems
 to be effective for the following reasons;

(i).  Many of the characteristic features of each style can be deduced from the ground plan of the building, the method is, therefore, applicable to ruined fortifications,
for which the ground plan survives. This accounts for a large number of remaining medieval examples.

(ii).   For strategic reasons, medieval fortifications were often built, in geometric patterns, across different locations(***). There seems to be reasonable evidence for this theory,
 in the case of fortifications around Denmark. Understanding these geometric patterns can allow the method to be applied to extant fortifications, also accounting for a
large number of examples.

(iii).   Some distinctive observable features are usually preserved, even in heavily restored or reconstructed medieval buildings, for which there are, again, many examples.
This provides a reasonable classification, in conjunction with historical or archeological information about the building's original construction. 

Features that are characteristic of these styles;

1. Viking; circular, shell type fortifications. 2. Norman; corner towers, rectangular keeps, embrasures and buttresses.  3. Concentric; concentric fortifications, multiple
towers, radiating designs. 4. Geometric; Non-concentric, quatrefoil designs. 5. Lancet; (fortified) single towers, typically placed in strategic positions. 6.  Regional
Scandinavian; characteristic stepped roofing on fortifications (and churches), simple wooden constructions, adaptations of Viking style. 7. Motte and Bailey; circular
keep on a hill, usually surrounded by a pallisade, often temporary constructions, mainly built (c1066-1150)

Historical references used in my research; (i). Denmark-you'll love it! Danish castles and Manor Houses, Bernhard Linder.
                                                               (ii). Crusader Castles, Robin Fedden, John Thomson.
                                                               (iii). Castles of Denmark, Chateau Gaillard: Etudes de 12th C castellogie medievale, Nils Engberg.
                                                               (iv). Nyborg castle museum.
                                                               (v). Plaque at Vordingberg tower.
                                                               (vi). Liber Census Daniae, 13th century.
                                                               (vii). Wikipedia.

               1.  Regional                                          Dunollie, Dunstaffnage, Urquhart
               2.  Norman                                          Sween, Tioram, Mingary, Innischonnel, Carnasserie, Kilchurn
               3.  Motte and Bailey                             Rothesay
               4.  Norwegian                                      Old Wick, Cubbie Roo, Kilmartin
               5.  Geometric                                       Inverlochy                   
               6.  Concentric                                      Bothwell          
               7.  Border                                            HermitageTantallon, Crichton, Craigmillar
               8.  Lancet                                            Eilean Donan, Douart, Stalker
                                                                          Edinburgh, Doune,  Aberdour, Lismore, 

Norman;       Corner buttresses, grey stone, rectangular.
Norwegian;   Two corner towers on a diagonal, stepped roofing, sharp contours,   
Border;         Broad defensive wall,

Clan history;  MacDougall, MacDonald, Campbell, MacRuari, MacSween, MacKenzie(not Norman descent)

Geometric Patterns;  Strategic positioning along diagonals, in particular (i). Loch Awe, (ii). Series of lochs, north west of the great glen. (iii).  Loch Duich to the Firth.
Historical References;   (i).  Scotland's Castles, Chris Tabraham.
                                    (ii). Castles and Ancient Monuments of Scotland, Damien Noonan.                         
                1. Neolothic (c1600BC)                        Belas Knap (plan)  (****) 
                2. Iron Age (Celtic) (c1300-500BC)     Cadbury           
                3. Motte and Bailey                               Totnes, Warwick, Kilpeck, Brimpsfield
                4. Anglo-Norman                                  Exeter castle,
                5. Geometric                                         St. Briavels, Hemyock
                6. Norman  (1066-1180)                      Bere Ferrers, de la Rupe, Lydford, (interior view), Bickleigh,
                                                                            Tiverton towers 1 (detail), 2 and cistern, Warwick, corner tower of Lundy castle,
                                                                             corner tower at St. Michael's Mount
                7. Random                                            Flint, (plan), Northernhay, Beverston gateway
                8. Concentric                                        Northernhayouter, inner fortifications and keep of Old Sarum

(See descriptions here)

Wales;     1. Motte and Bailey                               Cardiff, Llandovery.
                2. Anglo-Norman    (1080-1440)          keep windows and arches of Goodrich (plan), archway of
                                                                             St. Briavels, splay window and tower of Grosmont, (*****), arch and tower of
                                                                             Abergavenny castle, (***). 
                3. Norman                                             keep windows, vaulting and corner tower  of Goodrich, Monmouth.
                4. Geometric                                         Monmouth (bridge), Llandovery (keep).
                5. Concentric          (c1116-1250)        ChepstowCaerphilly outer wall, (plan), Beaumaris, (plan), Skenfrith.,Narberth,(plan),
                                                                            Carmarthen (keep detail)

Poland;    1.  Response to Scandinavian (c1350)    Zuraw        

   (***)    The arch has a dogtooth point, suggesting an Anglo-Saxon influence, with the tower probably being hexagonal, a
                Norman feature connected to the concentric style.
  (****)   Technically a tomb, but may have used for defensive purposes
 (*****)  Differing from the pure Norman style in the adoption of Anglo-Saxon features, but this is a term usually used
                in the classifications of church architecture.