Behind the Baluarte del Príncipe we find the Cavalry Barracks, headquarters of the Dragons of Olivenza Regiment, for 12 squadrons with 40 horses each.
Like the King's Bakery, it is an 18th century building, constructed in the wake of the organisational reform of the Portuguese army during the reign of D. João V. Its appearance conforms to the neoclassical principles, which originated in Portugal as a result of the reconstruction work carried out in Lisbon after the earthquake of 1775, under the direction of the Prime Minister of D. José I, the Marquis of Pombal. Although its roots stem more from the sober Portuguese building tradition than from a neoclassical style whose theory was still in its infancy in Rome. The rhythmic repetition of the windows, set in sober and unadorned marble frames, and the absence of additions or decorations in any other part of the facade define this Pombaline style building that we could also call Portuguese protoneo-classical. A long façade appears torn horizontally in two superimposed lines of windows, which give the whole its sobriety and martial rhythm. The complex, on both the eastern and western façades, is divided in the middle by a staircase extending over the facade, breaking the monotony of the complex, allowing access to the upper floor from the outside via four flights of stairs: two on the left and two on the right, framing a semi-circular arch through which the ground floor is accessed.
The interior, on the upper floor, was the area that housed the dormitories for the troops. Its spacious halls have since been walled up for its current use first as a Secondary School and then as a Community College. It is divided into two long wings with a barrel vault. The only interior decoration appears on the lintels of the chimneys and on the window seats, in marble from the area.