Sofia Metro, 25th Anniversary (Bulgaria 2023)

Stamp Sofia Metro, 25th Anniversary it reflects the thematic directions:

An anniversary is the date on which an event took place or an institution was founded in a previous year, and may also refer to the commemoration or celebration of that event. For example, the first event is the initial occurrence or, if planned, the inaugural of the event. One year later would be the first anniversary of that event. The word was first used for Catholic feasts to commemorate saints. Most countries celebrate national anniversaries, typically called national days. These could be the date of independence of the nation or the adoption of a new constitution or form of government. The important dates in a sitting monarch's reign may also be commemorated, an event often referred to as a "Jubilee".

Railways - Transportation system made up of metal rails which is designed to allow trains to maneuver on the tracks from one location to the next.

A tram (also known as a streetcar or trolley in the United States and Canada) is a type of urban rail transit consisting of either individual railcars or self-propelled multiple unit trains that run on tramway tracks on urban public streets; some include segments on segregated right-of-way The tramlines or tram networks operated as public transport are called tramways or simply trams/streetcars. Due to their close similarities, trams are commonly included in the wider term light rail,which also includes systems separated from other traffic.