The City of London is a geographically small city within Greater London, England. The City's boundaries have remained almost constant since the Middle Ages, and hence it is now only a tiny part of the much larger London metropolis. It is often referred to as just the City or as the Square Mile, as it is almost exactly one square mile in area. In the medieval period the City was the full extent of London, and distinct from the nearby, but then separate, settlement of Westminster, which became the City of Westminster. The term London now refers to a much larger conurbation containing both 'cities'.

St Paul's Cathedral is an Anglican cathedral on Ludgate Hill, in the City of London, and the seat of the Bishop of London. The present building dates from the 17th century, and is generally reckoned to be London's fifth St Paul's Cathedral, although the number is higher if every major medieval reconstruction is counted as a new cathedral. The Whispering Gallery runs around the interior of the Dome and is 99 feet (30.2 m) above the cathedral floor. It is reached by 259 steps from ground level. It gets its name because a whisper against its wall at any point is audible to a listener with their ear held to the wall at any other point around the gallery. It is possible to climb the 530 steps to the golden gallery, where there is a panoramic view of London.

Her Majesty's Royal Palace and Fortress, more commonly known as the Tower of London (and historically as The Tower), is a historic monument in central London, on the north bank of the River Thames. It is located within the London Borough of Tower Hamlets and is separated from the eastern edge of the City of London by the open space known as Tower Hill. The Tower of London is often identified with the White Tower, the original stark square fortress built by William the Conqueror in 1078. However, the tower as a whole is a complex of several buildings set within two concentric rings of defensive walls and a moat. The tower's primary function was a fortress, a royal palace, and a prison (particularly for high status and royal prisoners, such as the Princes in the Tower and the future Queen Elizabeth I). This last use has led to the phrase "sent to the Tower" (meaning "imprisoned"). It has also served as a place of execution and torture, an armoury, a treasury, a zoo, the Royal Mint, a public records office, an observatory, and since 1303, the home of the Crown Jewels of the United Kingdom.

The London Eye, also known as the Millennium Wheel, is the tallest (135 metres (443 ft)) Ferris wheel in Europe, and has become the most popular paid tourist attraction in the UK, visited by over 3 million people a year. At the time it was erected it was the tallest Ferris wheel in the world. It is still described as "The world's tallest cantilevered observation wheel" (because the entire structure is supported by an A-frame on one side only) by its operators.

The Collegiate Church of St Peter at Westminster, which is almost always referred to by its original name of Westminster Abbey, is a large, mainly Gothic church, (it served as a cathedral from 1546 - 1556), in Westminster, London, just to the west of the Palace of Westminster. It is the traditional place of coronation and burial site for English monarchs.

The Anglican Church of St. Margaret, Westminster, is situated in the grounds of Westminster Abbey on Parliament Square, and is the parish church of the British Houses of Parliament in London. It is dedicated to Margaret of Antioch. Originally founded in the 12th century by Benedictine monks, so that local people who lived in the area around the Abbey could worship separately at their own simpler parish church. St. Margaret's was rebuilt from 1486 to 1523. It became the parish of the Palace of Westminster in 1614, when the Puritans of the 17th century, unhappy with the highly liturgical Abbey, chose to hold Parliamentary services in the more "suitable" St. Margaret's, a practice that has since continued.

The Royal Observatory, Greenwich was commissioned in 1675 by King Charles II. At this time the king also created the position of Astronomer Royal to serve as the director of the observatory and to "apply himself with the most exact care and diligence to the rectifying of the tables of the motions of the heavens, and the places of the fixed stars, so as to find out the so much desired longitude of places for the perfecting of the art of navigation." It is situated on a hill in Greenwich Park in Greenwich, London, overlooking the River Thames. British astronomers have long used the Royal Observatory as a basis for measurement: four separate meridians have been drawn through the building. The basis of longitude, the Prime Meridian, established in 1851 and adopted at an international conference in 1884, passes through the Airy transit circle of the observatory. It was long marked by a brass strip in the courtyard, now upgraded to stainless steel, and, since December 16, 1999, has been marked by a powerful green laser shining north across the London night sky.