• Brief description: Built in the beginning of the 20th century over the old cathedral (today the church crypt), the Almudena is a blend of different styles: neo-classical exterior, neo-Gothic interior (with very special colours) and a neo-Romanesque crypt. In addition to its colourful interior noteworthy are its slate cupola and the more than 100 columns in the crypt. In 2004 Prince Felipe and Letizia Ortiz were married here. You don't need to enter the museum or go up to the cupola. Visiting the cathedral and the crypt is sufficient. In front of the cathedral is El Anciano Rey de los Vinos (C/ Bailén 19), a legendary spot for enjoying a glass of wine with views of the Almudena. The outdoor seating is nice in summer, while inside the decor is very authentic. Very famous for their vermouth on tap (vermut de grifo) (3,50€), which is served with a free tapa.
• Cost: Entrance to the Cathedral is free, though a 1€ donation is requested. Entrance to the crypt (highly recommended) is 2€. 
• Length of visit: 1 hour.
• Hours: from 9am to 8:30pm every day except when there is mass (Weekdays, 12.00pm, 6.00pm and 7.00pm; Sundays and holidays 10.00am, 12:00pm, 1:30pm, 6.00pm and 7.00pm).
• How to get there: walking. It's in front of the Royal Palace (Metro Opera L2 and L5). Enter the cathedral on Calle Bailén no. 10 and the crypt on Calle Mayor.