Spanish Gothic-civil architecture is exemplified by the Tower of Juan II, erected between 1440 and 1465.

Like the Bastille or the Tower of London, this tower was a state jail and a symbol of the Hispanic monarchy's ultimate power, housing a unique roster of notable inmates in the fortress's most guarded enclosure.

It rests on a 13th-century tower with an Almohad-influenced Mudejar window. Three imposts separate its 80-metre tower into three levels.

It has battlements with Castilian coats of arms and circular sgraffito designs.

152 spiral stairs lead to the top. The spectacular 360o views of the city and its natural surroundings from the top make the effort worthwhile: a beautiful view of the old city of Segovia, the Sanctuary of La Fuencisla, built next to some rocks in the lower part of the city; the Jewish cemetery, preserved next to the old Jewish quarter; the Church of La Vera Cruz, an old Templar church with an unusual dodecagonal floor plan; the Monastery of El Parral and the neighborhoods of San Marc.