In an indoor location within the city of Sliven, Bulgaria, a large, rectangular pedagogical poster depicting an internal combustion engine is positioned centrally, angled slightly upwards

In an indoor location within the city of Sliven, Bulgaria, a large, rectangular pedagogical poster depicting an internal combustion engine is positioned centrally, angled slightly upwards. The poster, printed on aged, orange-hued paper, displays "ДВИГАТЕЛЬ" (ENGINE) in blue Cyrillic script at its top. The left side of the poster features a cutaway diagram of an assembled engine block and cylinder head, detailing internal components. The right side illustrates various disassembled engine parts, including a camshaft assembly, piston, connecting rod, and crankshaft. All depicted components are numbered with corresponding Cyrillic labels. The poster exhibits wear, fading, and minor surface imperfections consistent with age. It rests on a substantial, medium-brown wooden surface, likely a desk or workbench, which occupies the lower third of the frame and shows visible wood grain and wear. The background is a plain, light beige or off-white wall with subtle marks. A dark electrical cable descends from a partially visible dark fixture at the top edge of the image, running diagonally against the wall. No individuals are present in the scene.