Beneath the Sōbu Line viaduct in Sotokanda, stalls the width of a wardrobe still sell vacuum tubes, resistors and solder by the gram. They are the surviving grammar of a radio market that took shape here in the late 1940s, and they stand a two-minute walk from shops stacked with limited-run figurines. Any serious Akihabara Walking Tour begins with that juxtaposition, because it explains the district's logic: components first, culture second, both traded at street level, both priced to move. The neighbourhood occupies a modest grid — roughly one square kilometre of Chiyoda City, bounded by the Kanda River and the elevated rail lines that cut it into quadrants. Chūō-dōri runs through the middle as its spine, closed to cars on Sunday afternoons for much of the year. Density does the work. A single eight-storey building may hold a model-kit retailer, a rhythm-game floor, a secondhand manga vendor and a themed café, each occupying one tenancy, each announced only by a vertical sign in Japanese. A guided 秋葉原 街歩きツアー exists because the inventory is vertical and unlabelled in English; the interesting floors are rarely the ground ones. The architecture is functional rather than ornamental. Akihabara Radio Kaikan, rebuilt and reopened in 2014, remains the most quoted address in the quarter: ten floors of specialist tenants above the Electric Town exit. Yodobashi Akiba anchors the eastern side with nine retail levels. Super Potato keeps retro consoles and cartridges upstairs, with a playable arcade near the top. Older Tokyo persists at the edges. Kanda Myōjin, founded in 730 and moved to its present hillside in 1616, now sells circuit-blessing amulets to engineers. Mansei Bridge, completed in 1930, still carries traffic across the Kanda River. Akihabara Walking Tour tours tend to thread these fixed points — shrine, bridge, viaduct, tower block — into one legible route. Today the district functions as a working market rather than a preserved quarter. Rents shift, tenants rotate, and the retro-game floor that mattered in 2019 may now be a gachapon hall with hundreds of capsule machines in rows. That volatility is the reason travellers buy Akihabara Walking Tour tickets at all: a printed map stays accurate for about a season, while a guide's floor-by-floor knowledge is current. Among Tokyo landmarks, few reward local literacy so directly, and fewer still charge nothing for the streets themselves.