A military bunker located at Str. Uioara 3, Bloc M2, sc.5, Sector 4, Bucharest, Romania. The provided web search results do not contain specific, verifiable information about this particular structure at the given coordinates. The results mention a 'Romanian Underground Bunker' in Gurahont, Arad County, which is a different geographic location approximately 400 km from the specified coordinates in Bucharest.
No confirmed historical details, construction date, function, or technical specifications for this bunker in Sector 4 can be derived from the available information.