San Juan de Ulua

Cortes's fleet made landfall near this islet in 1519, and within decades the Spanish were fortifying it: San Juan de Ulua grew over three centuries into the largest fortress in New Spain, built from coral limestone quarried out of the reef, with bastions, moats, a keep and rings of walls guarding the empire's main Atlantic port against English, French and Dutch raiders - Hawkins and Drake among the visitors who left under fire. Its history then turns darker: after independence the fortress became a prison whose cells - the notorious dungeons remembered by names like El Purgatorio and El Infierno - held political prisoners under successive governments, and it was the last place in Mexico to fly the Spanish flag, surrendering only in 1825. Visitors walk the ramparts, the powder rooms, the water cisterns and the cell blocks, with the container port working noisily alongside and the Gulf beyond. Guides fill in the layers; the building itself, with coral fossils visible in its blocks, does the rest.

What you actually see

• The coral-stone walls - fossil reef cut into bastions.
• The cell blocks - the fortress's long career as a prison.
• The ramparts - views over the port and the Gulf.
• The keep and cisterns - the working core of the fortress.

When to go

November to April for tolerable heat and humidity; mornings before the sun turns the ramparts into a griddle. Closed Mondays.

Honest expectations

There is little shade and considerable walking on uneven stone. Interpretation is Spanish-first; guides at the entrance are worth hiring. The setting is an active container port, not a scenic harbour.

Nearby

Veracruz's malecon, zocalo and danzon evenings lie across the water; the aquarium and Boca del Rio are along the coast.