Sure, the 41-minute virtual tour of the Winchester Mystery House is cool and all, but if you want to really go for spooky, turn off the lights and start exploring the underground ossuaries below Paris. While physically closed to the public during this time of coronavirus, the virtual visit to the Catacombs of Paris is still open.
The history of the Paris Catacombs starts in the late eighteenth century, when major public health problems tied to the city's cemeteries led to a decision to transfer their contents to an underground site.
Paris authorities chose an easily accessible site that was, at the time, located outside the capital: the former Tombe-Issoire quarries under the plain of Montrouge. In operation since at least the fifteenth century and then abandoned, these quarries were a small part of the labyrinth that extended under the city over approximately 800 hectares. Preparation of the site and the organization of bone transfers were entrusted to Charles Axel Guillaumot, an inspector at the Department of General Quarry Inspection. The mission of this department, which had been founded on April 4, 1777, by Louis XVI, was to consolidate the abandoned quarries following major collapses of the ground under Paris in the mid-eighteenth century.
The first evacuations were made from 1785 to 1787 and concerned the largest cemetery in Paris, the Saints-Innocents cemetery, which had been closed in 1780 after consecutive use for nearly ten centuries. The tombs, common graves and charnel house were emptied of their bones, which were transported at night to avoid hostile reactions from the Parisian population and the Church. The bones were dumped into two quarry wells and then distributed and piled into the galleries by the quarry workers. Transfers continued after the French Revolution until 1814, with the suppression of parochial cemeteries, such as Saint-Eustache, Saint-Nicolas-des-Champs and the Bernardins Convent, in the center of Paris. They were begun again in 1840, during urban renovation by Louis-Philippe and the Haussmannian reconfiguration of the city from 1859 to 1860. The site was consecrated as the "Paris Municipal Ossuary" on April 7, 1786, and, from that time forward, took on the mythical name of "Catacombs", in reference to the Roman catacombs, which had fascinated the public since their discovery.
screengrab via Catacombs of Paris