Only parts of the Roman Londinium have so far been excavated and identified. The profane basilica (commercial and administrative center), a hall structure (160 × 50 m), was probably built under Trajan or Hadrian built on the north side of the forum. The first stone forum was built in 80 AD (renewed around 100 AD in five times its size). The Governor’s Palace at the Forum (at Cannon Street Station) was built around 85 AD (abandoned around 300 AD). The amphitheater was built around 100 AD, the foundations of which were discovered (1988) 4 m underground near Guildhall. A Mithras sanctuary from the 3rd century AD was excavated (1954) at Walbrook (re-erected with numerous sculptures in the Museum of London). A property (especially bathrooms) that existed from 200 to 500 (Lower Thames Street) is well preserved. The first fortification was a fort in the northwest in the early 2nd century AD, which was incorporated into the city walls built at the end of the 2nd century (they enclosed an area of around 130 hectares); 350 to 370 they were strengthened in the east by bastions and they were also built along the Thames (renewed in the south-east around 390). The exposed sections of the wall often show parts that were added in the Middle Ages.
Under William the Conqueror, the Tower of London (with White Tower, central Keep and Saint John Chapel) and 1097-99 Westminster Hall, from which the arcaded side walls have been preserved (UNESCO World Heritage Site), were built under William the Conqueror.
From the church of the Augustinian monastery of Saint Bartholomew-the-Great (built in 1123 north of the medieval city) the two transepts and the choir with gallery have been preserved (a fine example of Norman architecture). South of the Thames in Southwark (connected to London by a stone bridge since 1176), an Augustinian monastery was built as early as 1106, with the choir, gallery, transept (13th century) and crossing tower and choir screen (around 1520) as parts of its second (Gothic) church what is now Southwark Cathedral. The also early Gothic rotunda of Temple Church was consecrated in 1185, its ribbed vaulted hall choir with slender bundle pillars made of Purbeck marble (from the southern English peninsula Isle of Purbeck) in 1240.
According to topb2bwebsites, a completely new construction of Westminster Abbey (UNESCO World Heritage Site) based on the model of French cathedrals began in 1245 under King Henry III. by Henry of Reyns (Reims) as a high-Gothic transept basilica, the construction of which was completed in 1269 to the rood screen, while the western part was only built in 1376-1422 and 1468-1502. In 1503–12, the Lady Chapel was added to the east under King Henry VII (the gothic west facade was only added by N. Hawksmoor in 1734–35; the interior was decorated with magnificent tombs from the 13th – 15th centuries).
The medieval expansion of the district of Westminster to the place of representation of the English monarchy was continued in 1394-1401 with the new construction of Westminster Hall (with an open roof made of oak). North of the abbey, the parish church of Saint Margaret was built in 1480–1523(UNESCO World Heritage Site) as a flat-roofed late Gothic basilica in forms of the late perpendicular style. 1411–40 the late Gothic Guildhall (town hall) was built over a vaulted basement as a hall decorated with rich tracery with (now reconstructed) buttress arches; In 1788 it was given a neo-Gothic facade. Of the new courts of justice built after the Reformation in the former settlement of the Knights Templar and in Lincoln’s Inn, the Hall (1562-70; with an open roof in Renaissance shapes) in the Middle Temple and the Old Hall (1490) and the chapel (1619) in Lincoln’s Inn -23). In the area of Westminster, Saint James’s Palace was built as a brick building in clear early Renaissance forms in the 16th century. I. Jones built Banqueting House (allegorical ceiling painting of the banquet hall 1634 by P. P. Rubens).
With the expansion of the urban area to the west, the first squares (places, often with trees) were laid out along the “beach”, for example in 1631 Covent Garden with the church of Saint Paul by I. Jones and Lincoln’s Inn Fields with the Lindsey House from 1640.
The great city fire of 1666, in which 13,000 houses were destroyed, resulted (by 1700) in an extensive structural renovation of the old town with brick buildings, with 51 parish churches also being built by C. Wren, mostly as hall churches and towers with steep helmets. His most important work was the new Baroque building of Saint Paul’s Cathedral (1675-1711, a combination of a transept basilica and a central dome with a western group of two towers). The most important secular building of this time is Chelsea Hospital (founded in 1681 as a veteran institution based on the model of the Hôtel des Invalides in Paris), which C. Wren built in 1682–89 as a three-winged facility in brick; from 1696 he then built Greenwich Hospital for the Navy.
Of the planned (law on financing 1711) another 50 city churches, especially in the newly developed areas north and west of the old town, only twelve were carried out, including by N. Hawksmoor Saint Anne, Limehouse, Saint George, Bloomsbury, and Christ Church, Spitalfields, as hall rooms with tall towers; J. Gibbs oriented himself with Saint Mary-le-Strand (1714-17) more closely to Italian baroque buildings of the 17th century and combined in Saint Martin-in-the-Fields (1722-26) a rectangular body decorated with pilasters with a Roman temple porch.
After Soho with its right-angled street network had already been laid out in the late 17th century, the adjacent lands were also included in a regular urban planning in the 18th century: New Bond Street and Hanover Square were laid out in 1720, with the church of Saint George (until 1724; Palladian portico); Grosvenor Square followed in 1725 and the Berkeley Square area in 1733. Another urban area developed in Westminster, which from 1738 was connected to the right bank of the Thames by a bridge. The most important public buildings were the Horse Guard barracks (from 1751) based on plans by W. Kent and Somerset House (1776) based on the Italian Baroque. Starting in 1773, Portland Square was built by R. and J. Adam in a restrained decorative style, while J. Nash (since 1812) with Park Crescent and Cumberland Terrace at Regent’s Park and Carlton House Terrace at Saint James’s Park achieved an interweaving of classic urban architecture with the public parks designed in the English landscape style. In the style of the Greek Revival, the church of Saint Pancras (1818-20; with clear references to the shape of the Athenian Erechtheion), the British Museum and on Trafalgar Square (1828) with the Nelson Column (1840-43) the National Gallery (1838, Dome 1887).