I visited Mexico between February and April 2019. I visited most WH colonial towns around Mexico City and Querétaro was the fourth one.

Querétaro is the most underwhelming town among Mexican WH cities and the one I enjoyed the least. It felt quite like every Mexican town to me, and I couldn't see the OUV. Monuments and churches in the center were either closed or boring, excepting maybe el Templo de Santa Rosa de Viterbo who as an interesting baroque exterior. Jardin Zenea and Plaza de la Constitucion were pleasant public squares, but doesn't deserve a stop in town by themselves. Under reviews bellow describe well my thoughts about Querétaro.

Otherwise, the most remarkable site (and the reason why this city deserved two instead of one star) is the aqueduct. It is gigantic and impressive (not Padre Tembleque level, but better than Morelia). It is 1,28 km long and has 74 highs arches. The view is particularly great from the mirador near el Mausoleo de la Corregidora.

Querétaro is conveniently located between San Miguel and Mexico City. You can also get here from Guadalajara, Morelia, Guanajuato, and San Luis Potosi. Former TWHS of Bernal is an easy day trip from here.