Portal (architecture) in the context of Column

A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is usually completely enclosed except for the two portals common at each end, though there may be access and ventilation openings at various points along the length. A pipeline differs significantly from a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods.

A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. The central portions of a rapid transit network are usually in the tunnel. Some tunnels are used as sewers or aqueducts to supply water for consumption or for hydroelectric stations. Utility tunnels are used for routing steam, chilled water, electrical power or telecommunication cables, as well as connecting buildings for convenient passage of people and equipment.

A lintel or lintol is a type of beam (a horizontal structural element) that spans openings such as portals, doors, windows and fireplaces. It can be a decorative architectural element, or a combined ornamented/structural item. In the case of windows, the bottom span is referred to as a sill, but, unlike a lintel, does not serve to bear a load to ensure the integrity of the wall.Modern-day lintels may be made using prestressed concrete and are also referred to as beams in beam-and-block slabs or as ribs in rib-and-block slabs. These prestressed concrete lintels and blocks can serve as components that are packed together and propped to form a suspended-floor concrete slab.

An arch functions as a curved lintel.

In classical architecture, an architrave (/ˈɑːrkɪˌtreɪv/; from Italian architrave 'chief beam'), also called an epistyle (from Ancient Greek ἐπίστυλον (epístulon) 'on the column'), is the lintel or beam, typically made of wood or stone, that rests on the capitals of columns.

The term can also apply to all sides, including the vertical members, of a frame with mouldings around a door or window. The word "architrave" has come to be used to refer more generally to a style of mouldings (or other elements) framing a door, window or other rectangular opening, where the horizontal "head" casing extends across the tops of the vertical side casings where the elements join (forming a butt joint, as opposed to a miter joint).

A gate or gateway is a point of entry to or from a space enclosed by walls. The word is derived from Proto-Germanic *gatan, meaning an opening or passageway. Gates may be designed for decorative or functional purposes, and they vary widely in style depending on architectural trends and material choices.

Synonyms include yett (which comes from the same root word) and portal. The concept originally referred to the gap or hole in the wall or fence, rather than a barrier which closed it. Gates may prevent or control the entry or exit of individuals, or they may be merely decorative. The moving part or parts of a gateway may be considered "doors", as they are fixed at one side whilst opening and closing like one.

The Palazzo San Giorgio or Palace of St. George (also known as the Palazzo delle Compere di San Giorgio) is one of the most important and well-known historic buildings in Genoa. It currently houses the headquarters of the Port System Authority of the Western Ligurian Sea.

The palace, included in the Molo district, is made up of two very distinct parts: an older part, a typical example of medieval civil architecture, with the façade facing the Sottoripa portico, and a Renaissance part, facing the sea, in which prospect, overlooking Via della Mercanzia, the short street that connects Piazza Caricamento and Piazza Cavour, near the ancient port, the main entrance portal opens.

The Hôtel de Marigny (French pronunciation: [otɛl də maʁiɲi]) is an hôtel particulier at 23 Avenue de Marigny in the 8th arrondissement of Paris, France, across the street from the Élysée Palace. It is used as a state guest house for state visitors to France and has been the property of the French government since 1972. Previously, state guests were housed at the Grand Trianon from 1959.

A trefoil arch, or three-foiled cusped arch (occasionally trilobite arch, no connection to an actual trilobite), is an arch incorporating the shape or outline of a trefoil – three overlapping circles. It has been widely used for its symbolic significance in Christian architecture. Trefoil arches are common in Gothic architecture for portals and decoration. Trefoil or "trilobed" arches are also a characteristic feature of decorated portals in late Fatimid architecture and Mamluk architecture in Egypt, from approximately the 12th to 16th centuries.

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  Trefoil arch in the choir of the parish Church of Saint-Eliphe (13th century), Rampillon, Seine-et-Marne (Ile-de-France)
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  Trefoil arches at the Bayeux Cathedral (11th century), Calvados, Normandy, France

A trocar (or trochar) is a medical or veterinary device traditionally used in draining or venting procedures, now also (informally termed a port) prominent in minimally invasive surgery. Trocars are typically made up of an obturator (which may be metal or plastic, and with a pointed or tapered tip), within a cannula (essentially a rigid tube), and often with a seal. They allow passive evacuation of excess gas or fluid from organs within the body; some also include a valve mechanism to allow for insufflation. Trocars designed for placement through the chest and abdominal walls during thoracoscopic and laparoscopic surgery function as portals for the subsequent insertion of other endoscopic instruments, such as grasper, scissors, stapler, electrocautery, suction tip, etc.