Yes, 55 cm is probably the frame size. (The color and size approximate those of my Bianchi.) Are those Columbus stickers on the fork blades? Look for some hint that the frame is made of Columbus, or at least its 3 main tubes are (Tre Tubi Rinforzati). I am guessing it is of circa 1990 vintage. If it fits you properly, it sounds like a keeper. If not, I am sure someone will help you find a nice home for it.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069