The Doa Urraca Tower, also known as the Fernán González Tower, is a building that can be found in the Spanish community of Covarrubias in the province of Burgos. Has the designation of Cultural Interest Good. Doa Urraca, the conde Fernán González's daughter, had reportedly been locked up, according to the leyenda in the tower.

It is situated in the historic town of Covarrubias in Castilla y León. This pyramidal structure has a rectangular base. Its appearance changes as it rises: the lower portion is made of large slabs of unlabeled stone, and on top of it is a zone of sillarejo that does not completely encircle the lienzo but instead rises to a height of about one-fourth of the tower while maintaining the rectangular sillar esquinas. The remaining sections of the parament are composed of very long sillera-to-soga hilts that alternate with shorter sillera-to-soga hilts and tizón hilts.

The lack of planning on the part of its muros contributes to the irregularity of the construction. This means that not only do the aristas not present a straight profile since they lose inclination towards the middle of the tower, but also that at the upper portion of the structure a slight concave curve joins the tejad. It is internally divided into two sections that are clearly distinguished by a cane bowed, and it is also divided into two levels that are separated by madera technology.

The entrance to the tower is located at the middle of its height, in the southern face that faces the river. It is a herradura arch with a peralte that is equal to the middle of the radio and that emerges erratically from the dovelas before convergent into points above the centre of the arch, each spaced a quarter of the radio apart. It was closer to the salmeres than the key, but it is now almost undetectable due to sillarejo erosion. This archway conceals an inner dintel with two hoary doors. A mobile staircase that had to be used to access this entrance would be removed in an emergency or whenever it was no longer necessary, leaving the tower as an impregnable and difficult-to-reach block that was well-prepared for defence. Then, during one of the later renovations, a factory escalator was built, starting in the middle of the base of the eastern side and ascending around the perimeter of the two eastern and western mummies. However, it was removed during the most recent restoration and is currently being climbed by another stone that is perpendicular to the tower and parallel to it.

To defend the tower, it must come to an end with an almenado adarve. Then, once the cubierta bóveda fell, it was rebuilt using the tejad that is currently in use and that has already been recorded in 19th-century recordings. The base is 10 by 14 metres on either side, which decreases to 7,50 by 11 metres at the top. The height reaches 22 metres, while the width is 3 metres.

Doa Urraca, the conde Fernán González's daughter, had reportedly been locked up, according to the leyenda in the tower.

After being designated a "Monumento Histórico-Artistico" on June 3, 1931, it is currently listed as a Cultural Good. The declaration was made on June 4th, 1931, and published in the Madrid Gazette by a decree signed by Marcelino Domingo, Minister of Public Instruction and the Arts, and Niceto Alcalá-Zamora, President of the Provisional Government of the Republic. The Colegiata de San Cosme y San Damián was declared with monuments from numerous other provinces, including another from Covarrubias.