Is it safe?
Zacatecas, Zacatecas
The short answer
The historic center of Zacatecas is calm and walkable, day and night. The thing to take seriously is the state, not the city. Zacatecas state has had real cartel violence for years, but it plays out on rural highways and in towns far from the capital, not on the cathedral steps. This is why we say fly into ZCL rather than drive across the state, and keep your days in and around the center.
Walking the center
By day you can walk the whole downtown without a second thought, the same as any busy Mexican city. After dark the main avenue, the cathedral area and the mezcal streets stay lively and lit, and you will not be alone. Stick to where the streetlights and people are. The lanes climb steeply and turn quiet a couple of blocks off the main drag, so at night keep to the routes that still have foot traffic rather than shortcutting up a dark alley.
The real risks
They are ordinary, not dramatic. Petty theft in crowded spots and around the market, phones left on café tables, that sort of thing. Watch your footing more than anything, the cobbles are uneven, the hills are steep, and at 2,400 meters you tire faster than you expect. If you rent a car, the honest caution is the open road: don’t drive intercity at night, and check current conditions before taking any highway across the state.
What a local would tell you
Stay in the center, use registered taxis or apps after dark instead of walking long distances back, and don’t wander out to the highway edges of town on foot. The downtown is one of the safest-feeling colonial cores in Mexico. It’s the drive in and out of the state that deserves your attention.