Carlos III's observatory on a hill at the edge of the Retiro: a neoclassical temple by Juan de Villanueva (begun 1790) with a Foucault pendulum, old instruments and a full-size replica of William Herschel's 60 cm telescope commissioned for it.
- Address
- Calle de Alfonso XII 3, 28014 Madrid
- Hours
- Guided visits only (90 min, in Spanish): Sep-May Fri 16:30, Sat 10:30, 12:30, 16:30, Sun 10:30, 12:30; Jun-Aug Sat-Sun 10:30, 12:30
- Best time to go
- Morning, Afternoon · About 1.5 h
- Price
- EUR 7 general, EUR 4 reduced, under-10s free (esmadrid.com 2026)
- Price level
- €€
Details can change. Check hours and prices before you go.
Good to know
- Visits are guided only and in Spanish; book on the IGN website.
- The Sunday 12:30 visit is a family version for children aged 7-12.