The find is apparently one of the largest of the last years. The floor that was found contains hundreds of tombstones, the oldest one is from 1596.

At the location there used to be the Nieuwezijds Kapel, a church founded in honour of the Miracle of Amsterdam. The church was built in 1345 on the remains of the house where the miracle happened, and broken down in 1908.

The current building is a Dutch reformed church, that has rented the building to the British company Merlin Entertainment. This company will open a new attraction called the Amsterdam Dungeon, this summer. It will be part of a chain of Dungeons, 3 in the UK and one in Hamburg, Germany.
The fact that this is a 'horror attraction' appears to be a coincidence.

The tombstones will soon be shown to the public. Some tombstones will probably be left visible, but most will disappear under the new building.