London's Tower Bridge was still stuck open early Tuesday, a day after a "technical failure" closed the 19th-century landmark, threatening to snarl traffic in the British capital. 

The two sections of the bridge have been pointing skyward since mid-afternoon on Monday, when they had been due to open for a tall wooden ship, the Sailing Vessel Tenacious, according to the bridge's schedule.

It is the second time in a year that the bridge, one of the most recognisable features of London's skyline, has become stuck.

A spokesperson for the City of London Corporation, which manages the bridge, told the BBC on Monday that investigations were taking place but the reason for the fault was unknown.

"Tower Bridge is currently closed to traffic and pedestrians due to technical failure. Please avoid the areas," City of London Police tweeted on Monday.

The bridge connects the Square Mile financial district to Southwark across the River Thames, and its closure caused long queues to build up on either side of the crossing.

Built between 1886 and 1894, the landmark was at the time considered "the largest and most sophisticated bascule bridge ever completed", according to its website.

The bascules - the word for the bridge's arms, derived from the French word for "seesaw" - move up and down via four large cogs on each side. The cogs were initially powered by steam before an electro-hydraulic system was installed in the 1970s.

The bridge normally lifts around 800 times a year.

In August 2020, it remained stuck for over an hour, causing traffic to become deadlocked in the surrounding areas.