Next to the church, Santuário de Nossa Senhora do Pranto, is this storybook tower.

From the zezeretrek.com web site, we learn:

"This locality (Dornes) is much older, having been Templar (12th century).
From this time it subsists its most outstanding symbol, the Pentagonal Tower,
ordered to be built by D. Gualdim Pais, Master of the Order of the Temple.
This tower had a watch function and was integrated in the defensive line of the Tagus
and its tributaries, that also included the Castles of Tomar,
Almourol and others of the region of Castelo Branco."