There are a number of dedicated PvP Zones around Tibia. PvP is allowed in these zones, even on no-pvp servers.

Deaths in PvP Zones will not result in any loss of items, exp or skills. The player will be teleported back to the temple.

Guildhalls

All Guildhalls have a dedicated PvP Zone arena that can only be accessed by those who are invited into the Guildhall.

Town Arenas

All towns have a PvP Zone arena.

Thais Knights Guild

Carlin Knights Guild

Kazordoon Fighting Pit

Abdendriel Bug Pen

Edron Magic Academy

Darashia Knights Guild

Venore Arena

Ankrahmun Arena

Port Hope Knights Guild

Open World

There are also a number of PvP Zones in the open world. These zones often require passing a protection zone to enter so they can not be exploited in real PvP.