This is thought to have existed already in Roman times. In the late Middle Ages it is called in manuscripts Sancti Petri. During the Middle Ages it is also called Porta Toletana ou Porta Toledana due to the fact that it lies on the road to Castille, mainly used by merchants from Toledo. Placed on a slope, it is 3.70 m. wide, its keystone is at 4.85 m., and the total height at this point is 10.80 metres.
Before it was rebuilt in 1781, it had lintels and wooden beams on top. Later on, it would have a guards room similar to the one in Porta Miñá, then turned into a chapel until it was eventuall pulled down in 1846. It is mainly an entry door, this justifies the ornament on the outside, such as a triangle-shaped frontispiece and the city's coat of arms, with the royal crown on top and two standing lions on both sides; it is placed on a cherub and an oval plaque indicated that the gate was rebuilt in 1781.
This gateway has been the main entry into the city for the thousands of pilgrims that have been coming to Compostela since the Middle Ages, along the Primitive Way to Santiago. This is also the beginning of the Castille Royal Road to Astorga. Through this gateway, the first lane on the right leads to Cantiño Square, with a starircase to the Wall.